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Artículos de revistas sobre el tema "Head out immersion"

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Publicado: 11 de marzo de 2023

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1

Rabelink, Ton J., Hein A. Koomans y Evert J. Dorhout Mees. "Role of prostaglandins in the natriuresis of head-out water immersion in humans". Clinical Science 80, n.º 5 (1 de mayo de 1991): 481–88. http://dx.doi.org/10.1042/cs0800481.

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1. Prostaglandins may play a role in the natriuresis seen after acute circulatory challenges. To assess this role in head-out water immersion, we compared, in clearance studies, the effects of acute (24 h) and chronic (7 days) administration of indomethacin, an inhibitor of prostaglandin synthesis, on the renal response to head-out water immersion in six healthy subjects on a 200 mmol of sodium/day diet and on a 40 mmol of sodium/day diet. 2. Indomethacin caused a similar degree of sodium retention on each of these two diets. 3. During the 40 mmol of sodium/day diet, acute administration of indomethacin decreased sodium excretion before, as well as during, head-out water immersion; however, the relative increase caused by head-out water immersion was normal. After chronic administration of indomethacin, both baseline sodium excretion and the natriuresis induced by head-out water immersion were similar to those in control studies. 4. During the 200 mmol of sodium/day diet, indomethacin had no effect on baseline sodium excretion, nor on the natriuretic effect of head-out water immersion. 5. Head-out water immersion decreased tubular lithium reabsorption and increased diluting segment delivery. Despite opposite effects of indomethacin on these parameters, indomethacin did not prevent the tubular effects of head-out water immersion on either diet. However, indomethacin did prevent the marked increase in estimated renal plasma flow and the fall in filtration fraction that were observed during head-out water immersion in the absence of indomethacin (control). 6. Head-out water immersion was not associated with an increase in urinary excretion of prostaglandins. Indomethacin lowered baseline urinary excretion of prostaglandins, which did not change further during head-out water immersion. 7. We therefore conclude that renal prostaglandins are not essential for a normal natriuretic response to head-out water immersion, although they may mediate the vasodilatation induced by head-out water immersion.

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2

Rabelink, Ton J., Karin A. van Tilborg, Ronald J. Hené y Hein A. Koomans. "Natriuretic Response to Head-Out Immersion in Humans with Recent Kidney Transplants". Clinical Science 85, n.º 4 (1 de octubre de 1993): 471–77. http://dx.doi.org/10.1042/cs0850471.

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1. Recently implanted kidneys may have decreased flexibility to adjust sodium excretion to volume challenges, since modulation by renal sympathetic nerve activity is absent. To examine this hypothesis, we studied the natriuretic response to head-out water immersion in eight patients with well-functioning renal allografts of 37 days (range 24–56 days), at a time when renal re-innervation has probably not occurred. 2. By the third hour of head-out water immersion, sodium excretion had increased equally in the patients (from 120 +21 to 204 +37 μmol/min) and in eight healthy control subjects (from 105 +9 to 191+19 μmol/min). 3. Glomerular filtration rate was 60 + 6 ml/min in the patients and 113 +6 ml/min in the control subjects, and did not change upon head-out water immersion. Estimated renal plasma flow increased upon head-out water immersion in the control group but not in the patients. Blood pressure decreased similarly in both groups. The renal vascular resistance, calculated from these data, decreased in response to head-out water immersion in the control subjects but not in the renal transplant patients. 4. Head-out water immersion suppressed plasma renin activity only in the normal group, whereas the plasma aldosterone level was suppressed in both groups. The natriuretic response in patients was associated with about 3-fold elevated plasma levels of atrial natriuretic peptide. 5. Since renal re-innervation at 37 days after transplantation is very unlikely, these data suggest that inact renal innervation is not mandatory for a normal natriuretic response to head-out water immersion in humans. However, sympathetic modulation might be involved in the decrease in renal vascular resistance and plasma renin activity normally observed during immersion.

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3

Christie, J. L., L. M. Sheldahl, F. E. Tristani, L. S. Wann, K. B. Sagar, S. G. Levandoski, M. J. Ptacin, K. A. Sobocinski y R. D. Morris. "Cardiovascular regulation during head-out water immersion exercise". Journal of Applied Physiology 69, n.º 2 (1 de agosto de 1990): 657–64. http://dx.doi.org/10.1152/jappl.1990.69.2.657.

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Head-out water immersion is known to increase cardiac filling pressure and volume in humans at rest. The purpose of the present study was to assess whether these alterations persist during dynamic exercise. Ten men performed upright cycling exercise on land and in water to the suprasternal notch at work loads corresponding to 40, 60, 80, and 100% maximal O2 consumption (VO2max). A Swan-Ganz catheter was used to measure right atrial pressure (PAP), pulmonary arterial pressure (PAP), and cardiac index (CI). Left ventricular end-diastolic (LVED) and end-systolic (LVES) volume indexes were assessed with echocardiography. VO2max did not differ between land and water. RAP, PAP, CI, stroke index, and LVED and LVES volume indexes were significantly greater (P less than 0.05) during exercise in water than on land. Stroke index did not change significantly from rest to exercise in water but increased (P less than 0.05) on land. Arterial systolic blood pressure did not differ between land and water at rest or during exercise. Heart rates were significantly lower (P less than 0.05) in water only during the two highest work intensities. The results indicate that indexes of cardiac preload are greater during exercise in water than on land.

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4

Giesbrecht, Gordon G., Tamara L. Lockhart, Gerald K. Bristow y Allan M. Steinman. "Thermal effects of dorsal head immersion in cold water on nonshivering humans". Journal of Applied Physiology 99, n.º 5 (noviembre de 2005): 1958–64. http://dx.doi.org/10.1152/japplphysiol.00052.2005.

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Personal floatation devices maintain either a semirecumbent flotation posture with the head and upper chest out of the water or a horizontal flotation posture with the dorsal head and whole body immersed. The contribution of dorsal head and upper chest immersion to core cooling in cold water was isolated when the confounding effect of shivering heat production was inhibited with meperidine (Demerol, 2.5 mg/kg). Six male volunteers were immersed four times for up to 60 min, or until esophageal temperature = 34°C. An insulated hoodless dry suit or two different personal floatation devices were used to create four conditions: 1) body insulated, head out; 2) body insulated, dorsal head immersed; 3) body exposed, head (and upper chest) out; and 4) body exposed, dorsal head (and upper chest) immersed. When the body was insulated, dorsal head immersion did not affect core cooling rate (1.1°C/h) compared with head-out conditions (0.7°C/h). When the body was exposed, however, the rate of core cooling increased by 40% from 3.6°C/h with the head out to 5.0°C/h with the dorsal head and upper chest immersed ( P < 0.01). Heat loss from the dorsal head and upper chest was approximately proportional to the extra surface area that was immersed (∼10%). The exaggerated core cooling during dorsal head immersion (40% increase) may result from the extra heat loss affecting a smaller thermal core due to intense thermal stimulation of the body and head and resultant peripheral vasoconstriction. Dorsal head and upper chest immersion in cold water increases the rate of core cooling and decreases potential survival time.

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5

Miki, K., K. Shiraki, S. Sagawa, A. J. de Bold y S. K. Hong. "Atrial natriuretic factor during head-out immersion at night". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 254, n.º 2 (1 de febrero de 1988): R235—R241. http://dx.doi.org/10.1152/ajpregu.1988.254.2.r235.

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The present investigation was undertaken to test the hypothesis that a circadian variation in the atrial natriuretic factor (ANF) response is responsible for the nocturnal inhibition of renal responses to head-out immersion (HOI). Plasma ANF responses to a 3-h HOI (water temperature 34.5 +/- 0.5 degrees C) were studied during day (1000-1300) and night (2400-0300) in six hydropenic male human subjects. In agreement with the previous observations, the renal responses, especially the diuresis, to HOI were attenuated at night compared with the day; furthermore, plasma renin activity decreased to the same low level during HOI at both day and night. Plasma ANF during time control periods was 30-40 pg/ml without showing any circadian variation. Moreover, plasma ANF showed a similar twofold increase within 1 h of HOI and was maintained at this elevated level throughout the 3-h HOI period in both the daytime and the nighttime series. On termination of HOI, plasma ANF decreased linearly to the pre-HOI level within 1 h. Hematocrit during time control periods was higher during the day compared with the night (P less than 0.05). Although HOI appears to induce a transient increase in plasma volume (as indicated by decreases in hematocrit) during the 1 h of HOI, the magnitude of the decrease in the latter parameters was not different between day and night. It is concluded that nocturnal inhibition of renal responses to HOI cannot be fully accounted for by circadian differences in the ANF and fluid shift response to HOI.

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6

Hayashi, N. y T. Miyamoto. "OXYGEN COST OF HYPERPNEA DURING HEAD-OUT WATER IMMERSION". Medicine & Science in Sports & Exercise 31, Supplement (mayo de 1999): S283. http://dx.doi.org/10.1097/00005768-199905001-01392.

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7

Shiraki, K., N. Konda, S. Sagawa, J. R. Claybaugh y S. K. Hong. "Cardiorenal-endocrine responses to head-out immersion at night". Journal of Applied Physiology 60, n.º 1 (1 de enero de 1986): 176–83. http://dx.doi.org/10.1152/jappl.1986.60.1.176.

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Cardiorenal-endocrine responses to 3-h head-out immersion (HOI) (water temperature = 34.5 +/- 0.5 degrees C) were studied during day (0900–1400 h) and night (2300–0400 h) in six hydropenic male human subjects. Although HOI induced a reversible increase in urine flow in all subjects, the response was faster and greater in magnitude during the day compared with night (P less than 0.05). Na excretion and osmolal clearance (Cosm) also followed the identical response pattern as urine flow, and in fact, the HOI-induced diuresis was entirely accounted for by the increased Cosm. Endogenous creatinine clearance was not different between the day and the night and remained unchanged during HOI. Both plasma renin activity and aldosterone concentration and urinary aldosterone excretion were nearly twofold greater during the day compared with night before HOI but decreased to the same level during HOI in both daytime and the nighttime series (P less than 0.05). There was no correlation between the Na excretion rate and renin-aldosterone levels either before or during HOI. Plasma antidiuretic hormone (ADH) level was comparable between day and night before HOI and decreased to a similar level during HOI in both daytime and nighttime series (P less than 0.05 for nighttime HOI). Cardiac output increased from 3.3 1/min before HOI to 5–6 1/min during HOI without showing any significant circadian difference. Hematocrit, hemoglobin, and plasma concentrations remained unchanged under all conditions. It is concluded that the renal response to HOI is subject to nocturnal inhibition, which cannot be attributed to circadian differences in the degree of HOI-induced central blood pooling, renin-aldosterone, or ADH responses.

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8

Ayme, Karine, Olivier Gavarry, Pascal Rossi, Anne-Virginie Desruelle, Jacques Regnard y Alain Boussuges. "Effect of head-out water immersion on vascular function in healthy subjects". Applied Physiology, Nutrition, and Metabolism 39, n.º 4 (abril de 2014): 425–31. http://dx.doi.org/10.1139/apnm-2013-0153.

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Immersion in thermoneutral water increases cardiac output and peripheral blood flow and reduces systemic vascular resistance. This study examined the effects of head-out water immersion on vascular function. Twelve healthy middle-aged males were immersed during 60 min in the seated position, with water at the level of xiphoid. Local and central vascular tone regulating systems were studied during that time. Brachial artery diameter and blood flow were recorded using ultrasonography and Doppler. Endothelial function was assessed with flow-mediated dilation. Results were compared with the same investigations performed under reference conditions in ambient air. During water immersion, brachial artery diameter increased (3.7 ± 0.2 mm in ambient air vs. 4 ± 0.2 mm in water immersion; p < 0.05). Endothelium-mediated dilation was significantly lower in water immersion than in ambient air (10% vs. 15%; p = 0.01). Nevertheless, the difference disappeared when the percentage vasodilatation of the brachial artery was normalized to the shear stimulus. Smooth muscle-mediated dilation was similar in the 2 conditions. Spectral analysis of systolic blood pressure variability indicated a decrease in sympathetic vascular activity. Plasma levels of nitric oxide metabolites remained unchanged, whereas levels of natriuretic peptides were significantly elevated. An increase in brachial blood flow, a decrease in sympathetic activity, a warming of the skin, and an increase in natriuretic peptides might be involved in the increase in reference diameter observed during water immersion. Endothelial cell reactivity and smooth muscle function did not appear to be altered.

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9

Epstein, M., P. Norsk, R. Loutzenhiser y P. Sonke. "Detailed characterization of a tank used for head-out water immersion in humans". Journal of Applied Physiology 63, n.º 2 (1 de agosto de 1987): 869–71. http://dx.doi.org/10.1152/jappl.1987.63.2.869.

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Water immersion has long been known to produce marked diuresis, natriuresis, and kaliuresis and suppression of the renin-aldosterone system. These effects are mediated primarily by an increase in central blood volume. Immersion has therefore gained increased acceptance in human physiology for the investigation of the effects of central volume expansion on renal function and hormonal responsiveness without altering the composition of the extracellular fluid. An immersion tank used for studies in humans is described. Requisite features to ensure study reproducibility include a constant temperature, capability to alter the depth of immersion by adjusting water height, and the ability to maintain hygienic quality by means of constant circulation of the water through a sand filter. A constant temperature of 34.5 +/- 0.2 degrees C is maintained by thermostatically controlling the heat exchange to a unidirectional closed-circuit water system in the bottom of the immersion tank coursing through a stream source. The level of the water may be adjusted to any desired level by means of a waste line or an inlet of tap water.

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10

Wada, F., S. Sagawa, K. Miki, K. Nagaya, S. Nakamitsu, K. Shiraki y J. E. Greenleaf. "Mechanism of thirst attenuation during head-out water immersion in men". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 268, n.º 3 (1 de marzo de 1995): R583—R589. http://dx.doi.org/10.1152/ajpregu.1995.268.3.r583.

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The purpose was to determine whether extracellular volume or osmolality was the major contributing factor for reduction of thirst in air and head-out water immersion in hypohydrated subjects. Eight males (19-25 yr) were subjected to thermoneutral immersion and thermoneutral air under two hydration conditions without further drinking: euhydration in water (Eu-H2O) and euhydration in air, and hypohydration in water (Hypo-H2O) and hypohydration in air (3.7% wt loss after exercise in heat). The increased thirst sensation with Hypo-H2O decreased (P < 0.05) within 10 min of immersion and continued thereafter. Mean plasma osmolality (288 +/- 1 mosmol/kgH2O) and sodium (140 +/- 1 meq/l) remained elevated, and plasma volume increased by 4.2 +/- 1.0% (P < 0.05) throughout Hypo-H2O. A sustained increase (P < 0.05) in stroke volume accompanied the prompt and sustained decrease in plasma renin activity and sustained increase (P < 0.05) in plasma atrial natriuretic peptide during Eu-H2O and Hypo-H2O. Plasma vasopressin decreased from 5.3 +/- 0.7 to 2.9 +/- 0.5 pg/ml (P < 0.05) during Hypo-H2O but was unchanged in Eu-H2O. These findings suggest a sustained stimulation of the atrial baroreceptors and reduction of a dipsogenic stimulus without major alterations of extracellular osmolality in Hypo-H2O. Thus it appears that vascular volume-induced stimuli of cardiopulmonary baroreceptors play a more important role than extracellular osmolality in reducing thirst sensations during immersion in hypohydrated subjects.

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11

Derion, T., H. J. Guy, K. Tsukimoto, W. Schaffartzik, R. Prediletto, D. C. Poole, D. R. Knight y P. D. Wagner. "Ventilation-perfusion relationships in the lung during head-out water immersion". Journal of Applied Physiology 72, n.º 1 (1 de enero de 1992): 64–72. http://dx.doi.org/10.1152/jappl.1992.72.1.64.

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Water immersion can cause airways closure during tidal breathing, and his may result in areas of low ventilation-perfusion (VA/Q) ratios (VA/Q less than or equal to 0.1) and/or shunt and, ultimately, hypoxemia. We studied this in 12 normal males: 6 young (Y; aged 20–29 yr) with closing volume (CV) less than expiratory reserve volume (ERV), and six older (O; aged 40–54 yr) with CV greater than ERV during seated head-out immersion. Arterial and expired inert gas concentrations and dye-dilution cardiac output (Q) were measured before and at 2, 5, 10, 15, and 20 min in 35 degrees C water. During immersion, Y showed increases in expired minute ventilation (VE; 8.3–10.3 l/min), Q (6.1–8.2 l/min), and arterial PO2 (PaO2; 91–98 Torr; P less than or equal to 0.05). However, O2 uptake (VO2), shunt, amount of low-VA/Q areas (% of Q), and the log standard deviation of the perfusion distribution (log SDQ) were unchanged. During immersion, O showed increases in shunt (0.6–1.8% of Q), VE (8.5–11.4 l/min), and VO2 (0.31–0.40 l/min) but showed no change in low-VA/Q areas, log SDQ, Q, or PaO2. Throughout, O showed more VA/Q inequality (greater log SDQ) than Y (O, 0.69 vs. Y, 0.47).(ABSTRACT TRUNCATED AT 250 WORDS)

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12

Liner, M. H. "Tissue gas stores of the body and head-out immersion in humans". Journal of Applied Physiology 75, n.º 3 (1 de septiembre de 1993): 1285–93. http://dx.doi.org/10.1152/jappl.1993.75.3.1285.

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Breath-by-breath gas exchange was studied in 10 subjects during and after transitions between dry conditions and head-out immersion in thermoneutral conditions. Cardiac index (CI) was estimated by means of impedance cardiography. Previous largely qualitative models of changes in tissue gas stores after blood volume shifts could be confirmed and extended to include a quantitative analysis of O2 and CO2 tissue stores. An increase in CI by 47.0% during immersion was associated with an increase in the tissue O2 stores by 122 ml/m2 and a decrease in the tissue CO2 stores by 148 ml/m2. The time constants for the recovery of O2 uptake (tau O2) and CO2 elimination after initial increases after the dry-to-immersion transition were 32.4 and 79.3 s, respectively. The decrease in CI on return to the dry conditions was associated with a drop in tissue O2 stores and a tau O2 of 144 s. The increase in tissue O2 stores during immersion as well as the difference in tau O2 between the two transitions were larger than could be explained by the change in CI only. This was attributed to changes in the distributions of peripheral blood flow and venous blood volume. Compared with the O2 stores, the decrease in CO2 stores was better predicted by the change in CI. The present results emphasize that the changes in pulmonary and tissue gas exchange imposed by head-out immersion transients mainly reflect movement of gas in and out of body stores.

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13

Hajduczok, G., K. Miki, J. R. Claybaugh, S. K. Hong y J. A. Krasney. "Regional circulatory responses to head-out water immersion in conscious dogs". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 253, n.º 2 (1 de agosto de 1987): R254—R263. http://dx.doi.org/10.1152/ajpregu.1987.253.2.r254.

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We determined the regional blood flow responses to head-out water immersion (WI) in intact (INT) and cardiac-denervated (CD) conscious dogs. Immersing dogs in thermoneutral water (37 degrees C) in the quadruped position for 100 min resulted in significant increases in cardiac output (Qco) above control values by 38.7% in the INT dogs and 39.2% in the CD dogs (P less than 0.01). Arterial pressure increased by 32 and 34.7% in the INT and CD groups, respectively, during WI, with no significant changes occurring in the calculated total peripheral resistance. Regional blood flow responses were measured with 15-microns radiolabeled microspheres. Flows in the INT and CD groups increased significantly to the heart (40, 38%), skin (93, 96%), fat (79, 83%), diaphragm (44, 48%), and intercostal muscles (58, 55%), whereas there were no changes in renal cortical blood flows during WI. Total brain blood flows did not change significantly on immersion; however, blood flows in both INT and CD animals were increased to the cerebellum (19, 22%), but a significant decrease in pituitary flow (52%) was observed only in the CD group during WI. Gastrointestinal tissue flows increased only during early WI in both INT (45%) and CD (47%) animals. However, blood flows to the skeletal muscles increased only during late WI in the INT (53%) and CD (47%) groups. There were no significant differences between the INT and CD groups. Rectal temperatures and systemic O2 consumption (VO2) were unchanged during WI in both groups of animals. These observations indicate that WI leads to a sustained elevation of Qco accompanied by selective increases in regional tissue perfusion that may be accounted for in some tissues by an increase in metabolic demand or by local heating responses and produces a time-dependent redistribution of blood flow away from the gastrointestinal tissues toward skeletal muscle tissues, which may be due to a partial uncoupling of the normal Q/VO2 relationship. This may be caused by thermal or central neurohumoral mechanisms. These regional circulatory responses are not dependent on the presence of the cardiac nerves.

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14

Warner, Leonard C., Gilles A. Morali, Judith A. Miller, Alexander G. Logan, Karl L. Skorecki y Laurence M. Blendis. "Aldosterone, atrial natriuretic factor and sodium intake as determinants of the natriuretic response to head-out water immersion in healthy subjects". Clinical Science 80, n.º 5 (1 de mayo de 1991): 475–80. http://dx.doi.org/10.1042/cs0800475.

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1. The effect of sodium intake on the natriuresis and hormonal changes induced by head-out water immersion was studied in seven normal subjects during head-out water immersion and on a control day while successively on 20 mmol of sodium/day and 100 mmol of sodium/day diets. The effects of head-out water immersion were compared with those seen on the control day for both diets. 2. The natriuresis on the 100 mmol of sodium/day diet was significantly greater than on the 20 mmol of sodium/day diet (natriuretic peak: 10.3 ± 2.2 versus 3.9 ± 1 mmol of sodium/h; P < 0.01). The total sodium excretion during the 3 h of head-out water immersion was 26.2 ± 2.0 mmol on the 100 mmol of sodium/day diet and 9.9 ± 0.9 mmol on the 20 mmol of sodium/day diet (P < 0.01). In contrast, the increase in the plasma atrial natriuretic factor level was similar on both diets (peak plasma atrial natriuretic factor level 23.1 ± 1.9 versus 26.2 ± 1 pg/ml; not significant). As expected, the baseline serum aldosterone level was higher on the 20 mmol of sodium/day diet and, despite a significant suppression, remained significantly higher at the end of the third hour of head-out water immersion (peak serum aldosterone level: 495 ± 130 versus 197 ± 26 pmol/l, P < 0.06). Furthermore, there was an inverse relationship between the serum aldosterone level and the urinary sodium excretion at the time of peak natriuresis (r = −0.59, P < 0.01). 3. We conclude that the effect of sodium intake on the natriuresis induced by head-out water immersion is more dependent upon anti-natriuretic agents, such as aldosterone, than on natriuretic factors, such as atrial natriuretic factor.

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Sackett, James R., Zachary J. Schlader, Suman Sarker, Christopher L. Chapman y Blair D. Johnson. "Peripheral Chemosensitivity is Not Blunted during Head Out Water Immersion". Medicine & Science in Sports & Exercise 49, n.º 5S (mayo de 2017): 288. http://dx.doi.org/10.1249/01.mss.0000517648.14583.f4.

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16

Millar, N. D., J. P. O'Hare, M. Wooder, J. C. MacKenzie y R. J. M. Corrall. "The Renal Effects of Head out Water Immersion in Pregnancy". Clinical Science 69, s12 (1 de diciembre de 1985): 68P. http://dx.doi.org/10.1042/cs069068pa.

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17

Choukroun, M. L. y P. Varene. "Adjustments in oxygen transport during head-out immersion in water at different temperatures". Journal of Applied Physiology 68, n.º 4 (1 de abril de 1990): 1475–80. http://dx.doi.org/10.1152/jappl.1990.68.4.1475.

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Respiratory gas exchange was investigated in human subjects immersed up to the shoulders in water at different temperatures (Tw = 25, 34, and 40 degrees C). Cardiac output (Qc) and pulmonary tissue volume (Vti) were measured by a rebreathing technique with the inert gas Freon 22, and O2 consumption (VO2) was determined by the closed-circuit technique. Arterial blood gases (PaO2, PaCO2) were analyzed by a micromethod, and alveolar gas (PAO2) was analyzed during quiet breathing with a mass spectrometer. The findings were as follows. 1) Immersion in a cold bath had no significant effect on Qc compared with the value measured at Tw = 34 degrees C, whereas immersion in a hot bath led to a considerable increase in Qc. Vti was not affected by immersion at any of the temperatures tested. 2) A large rise in metabolic rate VO2 was only observed at Tw = 25 degrees C (P less than 0.001). 3) Arterial blood gases were not significantly affected by immersion, whatever the water temperature. 4) O2 transport during immersion is affected by two main factors: hydrostatic pressure and temperature. Above neutral temperature, O2 transport is improved because of the marked increase in Qc resulting from the combined actions of hydrostatic counter pressure and body heating. Below neutral temperature, O2 transport is altered; an increase in O2 extraction of the tissue is even calculated.

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18

Pretorius, Thea, Farrell Cahill, Sheila Kocay y Gordon G. Giesbrecht. "Shivering Heat Production and Core Cooling During Head-In and Head-Out Immersion in 17°C Water". Aviation, Space, and Environmental Medicine 79, n.º 5 (1 de mayo de 2008): 495–99. http://dx.doi.org/10.3357/asem.2165.2008.

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Hess, Hayden W., Zachary J. Schlader, Lindsey N. Russo, Rebeccah L. Stansbery, Mary G. Carey, David R. Pendergast, Brian M. Clemency y David Hostler. "Effect of rehydration schedule after four-hour head-out water immersion on running performance and recovery". Undersea and Hyperbaric Medicine 45, n.º 5 (1 de septiembre de 2018): 495–503. http://dx.doi.org/10.22462/9.10.2018.2.

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Introduction: Head-out water immersion (HOWI) results in diuresis, which could potentially limit performance after egress to land. We examined the effect of rehydration on endurance, cardiovascular stability, and overnight recovery following a four-hour thermoneutral HOWI on 12 subjects. Methods: Twelve males completed a crossover design consisting of no hydration, replacement of fluid loss during immersion (RD), and replacement of fluid after the immersion period (RA). Sixty minutes following immersion, subjects ran to exhaustion at ~80% maximum heart rate. After completing the run, each subject submitted to a head-up tilt test (HUTT). Vital signs and ECG were monitored overnight. Results: HOWI resulted in a transient diuresis in NH and RA, while it was sustained throughout immersion in the RD protocol, resulting in greater urine [l] output (1.27 ± 0.48 (NH), 1.18 ± 0.43 (RA), 2.32 ± 0.77 (RD) (p < 0.001). Body mass change (%) was greater in NH than RD, but not RA (-1.58 ± 0.56 (NH), -0.66 ± 0.47 (RD), and -0.92 ± 0.76 (RA)). Run times were 17% versus 20% in NH compared to RD and RA, respectively, but were not statistically different. Time to orthostasis during the HUTT did not differ by condition. Overnight heart rate variability and blood pressure were not different. Conclusion: Rehydration during water immersion resulted in a large, sustained diuresis without improving performance or recovery after exiting the water. Loss of body water during thermoneutral HOWI was modest, and both rehydration strategies minimally affected aerobic performance and overnight recovery in young, healthy males.

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20

Rabelink, T. J., H. A. Koomans, P. Boer, C. A. Gaillard y E. J. Dorhout Mees. "Role of ANP in natriuresis of head-out immersion in humans". American Journal of Physiology-Renal Physiology 257, n.º 3 (1 de septiembre de 1989): F375—F382. http://dx.doi.org/10.1152/ajprenal.1989.257.3.f375.

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Atrial natriuretic peptide (ANP) may play a role in the natriuresis after acute circulatory challenges. To assess this role in head-out water immersion (HOI), we compared in clearance studies the effect of 3 h HOI with an equally natriuretic 3-h infusion of ANP [0.01 microgram.kg-1.min-1 human ANP-(99-126)] in seven healthy individuals taking a 100 mmol sodium diet. The studies were repeated after treatment with enalapril (20 mg twice daily), which in previous studies inhibited the natriuresis after ANP. HOI caused a natriuresis equal to that of ANP infusion despite an about five times smaller rise in plasma ANP. HOI increased and ANP decreased estimated renal plasma flow (ERPF). HOI increased maximal free water clearance and decreased fractional lithium reabsorption. ANP did not affect these variables but raised minimal urine osmolality. Enalapril enhanced the fall in ERPF caused by ANP and abolished its natriuretic effect; enalapril did not impair either the natriuresis after HOI or the increase in ERPF and the fall in lithium reabsorption. These data indicate that the low dosage of ANP causes natriuresis by reducing sodium absorption in a distal nephron target segment; enalapril impairs this effect, perhaps by enhancing ANP-induced vasoconstriction, which decreases delivery to this target segment. HOI, by increasing sodium delivery to this segment, is natriuretic despite only a small rise in plasma ANP. Enalapril does not impair these effects. Although a rise in plasma ANP may be one factor in the natriuresis of HOI, the present data speak against an exclusive role. Other factors determine the magnitude of the natriuretic response.

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21

Sheldahl, L. M., F. E. Tristani, P. S. Clifford, J. H. Kalbfleisch, G. Smits y C. V. Hughes. "Effect of head-out water immersion on response to exercise training". Journal of Applied Physiology 60, n.º 6 (1 de junio de 1986): 1878–81. http://dx.doi.org/10.1152/jappl.1986.60.6.1878.

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During spaceflight and head-out water immersion (WI) there is a cephalad shift in blood volume. We have recently shown that left ventricular end-diastolic dimension is significantly greater during moderate cycling exercise with WI compared with on land. The purpose of this study was to determine whether the cephalad shift in blood volume and accompanying increase in cardiac preload with WI alters the normal cardiovascular adaptations to aerobic exercise training. Nine middle-aged healthy men trained on cycle ergometers in water, nine trained on land, and four served as controls for 12 wk. Following training, both training groups showed similar increase (P less than 0.05) in stroke volume and similar decreases in heart rate (P less than 0.01) and blood pressure (P less than 0.05) at a given submaximal exercise O2 consumption (VO2). Maximal VO2 increased (P less than 0.01) similarly for both training groups. The control group did not demonstrate any significant changes in submaximal or maximal exercise responses. We conclude that the cephalad shift in blood volume with WI does not alter the normal cardiovascular adaptation to aerobic exercise training.

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22

Park, Y. S., J. K. Choir, J. S. Kim y S. K. Hong. "Renal response to head-out water immersion in Korean women divers". European Journal of Applied Physiology and Occupational Physiology 67, n.º 6 (diciembre de 1993): 523–27. http://dx.doi.org/10.1007/bf00241649.

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23

Miki, K., G. Hajduczok, S. K. Hong y J. A. Krasney. "Plasma volume changes during head-out water immersion in conscious dogs". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, n.º 3 (1 de septiembre de 1986): R582—R590. http://dx.doi.org/10.1152/ajpregu.1986.251.3.r582.

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Blood volume (51Cr-erythrocyte dilution method), hematocrit, and arterial (Pa), central venous (Pv), plasma colloid osmotic (IIpl), and interstitial fluid hydrostatic (Pcps, Guyton's capsule method) pressures were measured continuously to determine the kinetics of the transvascular fluid shift during 100 min of water immersion (WI) at 37 degrees C in six splenectomized dogs. Urine flow increased by 180% above control levels (P less than 0.05) by 30 min of WI. Plasma volume (PV) started to increase at 5 min of WI and rose by 7.2% (P less than 0.05) above control levels by 35 min of WI, and then it decreased gradually. PV returned to control levels immediately after WI. Plasma protein concentration and IIpl decreased significantly by 0.2 g/100 ml and 1.2 mmHg, respectively, at 35 min of WI, while plasma osmolality and Na+ concentration were constant. Pa and Pv increased (P less than 0.05) by 25 and 12 mmHg, respectively. Mean capillary pressure, which was calculated from Pa, Pv, and an estimated pre-to-postcapillary resistance ratio of 5-12, increased by 13-14 mmHg while Pcps increased (P less than 0.05) by 17 and 26 mmHg at upper hindlimb and lower forelimb, respectively. The changes in mean capillary pressure and IIpl tend to promote capillary filtration in WI; however, the greater elevation of Pcps more than offsets these forces and leads to a net transvascular shift into the plasma compartment.

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24

TAJIMA, Fumihiro, Hajime OGATA, Kenju MIKI, Kazunari ENISHI y Keizo SHIRAKI. "Changes in Limb Volume during Head-Out Water Immersion in Humans". Journal of UOEH 11, n.º 2 (1989): 145–53. http://dx.doi.org/10.7888/juoeh.11.145.

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25

Bisson, D. L., G. D. Dunster y J. P. O'Hare. "The Renal Response to Head Out Water Immersion in Gestational Diabetes". Clinical Science 79, s23 (1 de octubre de 1990): 6P. http://dx.doi.org/10.1042/cs079006p.

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26

Chouchou, Florian, Vincent Pichot, Frédéric Costes, Mailys Guillot, Jean-Claude Barthélémy, Laurent Bertoletti y Frédéric Roche. "Autonomic cardiovascular adaptations to acute head-out water immersion, head-down tilt and supine position". European Journal of Applied Physiology 120, n.º 2 (7 de diciembre de 2019): 337–47. http://dx.doi.org/10.1007/s00421-019-04278-4.

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27

Tipton, M. J., D. A. Stubbs y D. H. Elliott. "The Effect of Clothing on the initial Responses to Cold Water Immersion in man". Journal of The Royal Naval Medical Service 76, n.º 2 (junio de 1990): 89–95. http://dx.doi.org/10.1136/jrnms-76-89.

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AbstractThe protection provided by three clothing assemblies against the cold shock response was investigated. Nine healthy male volunteers each undertook three two minute head-out immersions into stirred water at 10°C. The subjects wore a different clothing assembly for each immersion, these were: (a)Swimming trunks only;(b)Conventional clothing (equivalent to RN No 8s);(c)Conventional clothing plus windproof/showerproof clothing (RN foul-weather clothing Mk III).The cardiac, ventilatory and thermal responses of the subjects were examined before and during the immersions.No significant differences were found between the magnitude of the responses recorded on immersion when conventional clothing or foul-weather clothing were worn. Mean skin temperature was lower (P<0.05) and respiratory frequency and minute ventilation were higher (P<0.05) on immersion in swimming trunks compared to the other two conditions.It is concluded that when policies for the use of immersion protective clothing are being formulated, consideration should be given to all of the potentially hazardous responses associated with cold water immersion.

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28

Rim, Hark, Young Min Yun, Kyoung Min Lee, Jeoung Taek Kwak, Do Whan Ahn, Jang Kyu Choi, Kyoung Ryong Kim, Young Duk Joh, Jee Yeun Kim y Yang Saeng Park. "Effect of Physical Exercise on Renal Response to Head-Out Water Immersion." APPLIED HUMAN SCIENCE Journal of Physiological Anthropology 16, n.º 1 (1997): 35–43. http://dx.doi.org/10.2114/jpa.16.35.

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29

Pendergast, D. R., A. J. de Bold, M. Pazik y S. K. Hong. "Effect of Head-Out Immersion on Plasma Atrial Natriuretic Factor in Man". Experimental Biology and Medicine 184, n.º 4 (1 de abril de 1987): 429–35. http://dx.doi.org/10.3181/00379727-184-42497.

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30

Mourot, Laurent, Malika Bouhaddi, Emmanuel Gandelin, Sylvie Cappelle, Gilles Dumoulin, Jean-Pierre Wolf, Jean Denis Rouillon y Jacques Regnard. "Cardiovascular Autonomic Control During Short-Term Thermoneutral and Cool Head-Out Immersion". Aviation, Space, and Environmental Medicine 79, n.º 1 (1 de enero de 2008): 14–20. http://dx.doi.org/10.3357/asem.2147.2008.

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31

Tajima, F., S. Sagawa, J. Iwamoto, K. Miki, J. R. Claybaugh y K. Shiraki. "Renal and endocrine responses in the elderly during head-out water immersion". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 254, n.º 6 (1 de junio de 1988): R977—R983. http://dx.doi.org/10.1152/ajpregu.1988.254.6.r977.

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After overnight food and fluid restriction, seven healthy old (62-74 yr) and eight young (21-28 yr) men were examined before, during, and after 3-h head-out immersion (HOI) in thermoneutral water (34.5 +/- 0.5 degrees C). On separate days, all subjects remained seated in air for 5 h to obtain the time control data. Although HOI induced a reversible increase in urine flow in all subjects, the response was faster and greater in magnitude in the elderly than in the young. Na excretion and osmolal clearance also followed a response pattern identical to that of urine flow; thus the HOI-induced diuresis was entirely osmotic. Endogenous creatinine clearance increased in the elderly at 2 h of HOI, suggesting an age-related modification in kidney hemodynamics. Although there was virtually the same cephalad blood shift (measured by impedance cardiography), mean arterial pressure significantly increased (P less than 0.05) during HOI in the elderly, which also indicated a different response of peripheral circulation to HOI in the elderly. Control level of plasma atrial natriuretic factor (ANF) was nearly twofold greater in the elderly compared with the young. The HOI induced a nearly fourfold increase in ANF in the elderly, whereas that for the young was threefold. Both plasma aldosterone and ADH responses to HOI were attenuated in the elderly compared with the young, which had no correlation with urine flow or Na excretion. It is concluded that the elderly release more ANF at a given cephalad volume expansion compared with the young, but the vasodilative reaction to ANF was attenuated in the elderly.

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32

Miki, K., M. R. Klocke, S. K. Hong y J. A. Krasney. "Interstitial and intravascular pressures in conscious dogs during head-out water immersion". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 257, n.º 2 (1 de agosto de 1989): R358—R364. http://dx.doi.org/10.1152/ajpregu.1989.257.2.r358.

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Water immersion (WI) causes an increase in plasma volume in humans and dogs. To determine the mechanism for this fluid movement, the transmission of external water hydrostatic pressure to the interstitial and vascular compartments was studied in six conscious dogs. Systemic arterial, central venous, peripheral arterial (ulnar artery) and venous (cephalic vein), pleural, intra-abdominal, and interstitial fluid hydrostatic (by Guyton's capsule and wick catheter method) pressures and external reference water pressure were measured at three different levels of WI: 1) extremities only, 2) midchest, and 3) midcervical levels at 37 degrees C. There was a significant linear relationship between interstitial fluid hydrostatic pressure (X) and external water pressure (Y): (Y = 0.86X + 1.4, r = 0.93 by Guyton's capsule; Y = 0.85X + 2.4, r = 0.93 by wick catheter. However, vascular pressures did not change when dogs were immersed at the level of the extremities. These pressures increased only during WI at the midchest and midcervical levels. Therefore the pressure gradient that develops between the interstitial and intravascular compartments is probably the major reason for the transcapillary fluid shift during WI.

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33

van Tilborg, Karin A., Ton J. Rabelink y Hein A. Koomans. "Naloxone inhibits renal hemodynamic effect of head-out water immersion in humans". Kidney International 48, n.º 3 (septiembre de 1995): 860–65. http://dx.doi.org/10.1038/ki.1995.362.

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34

Kruel, Luiz F. M., Leonardo A. Peyré-Tartaruga, Marcelo Coertjens, Adriana B. C. Dias, Rafael C. Da Silva y Antônio C. B. Rangel. "Using Heart Rate to Prescribe Physical Exercise During Head-Out Water Immersion". Journal of Strength and Conditioning Research 28, n.º 1 (enero de 2014): 281–89. http://dx.doi.org/10.1519/jsc.0b013e318295d534.

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35

Tajima, F., S. Sagawa, J. Iwamoto, K. Miki, J. R. Claybaugh y K. Shiraki. "Renal and Endocrine Response in the Elderly During Head-Out Water Immersion". Journal of Urology 141, n.º 3 Part 1 (marzo de 1989): 683–84. http://dx.doi.org/10.1016/s0022-5347(17)40957-8.

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36

Sheldahl, Lois M., Felix E. Tristani, Philip S. Clifford, C. Vincent Hughes, Kathleen A. Sobocinski y Robert D. Morris. "Effect of head-out water immersion on cardiorespiratory response to dynamic exercise". Journal of the American College of Cardiology 10, n.º 6 (diciembre de 1987): 1254–58. http://dx.doi.org/10.1016/s0735-1097(87)80127-4.

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37

Kojima, Daisuke, Takeshi Nakamura, Motohiko Banno, Yasunori Umemoto, Tokio Kinoshita, Yuko Ishida y Fumihiro Tajima. "Head-out immersion in hot water increases serum BDNF in healthy males". International Journal of Hyperthermia 34, n.º 6 (20 de noviembre de 2017): 834–39. http://dx.doi.org/10.1080/02656736.2017.1394502.

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38

Rascher, Wolfgang, Tivadar Tulassay, Hannsjörg W. Seyberth, Urban Himbert, Uwe Lang y Karl Schärer. "Diuretic and hormonal responses to head-out water immersion in nephrotic syndrome". Journal of Pediatrics 109, n.º 4 (octubre de 1986): 609–14. http://dx.doi.org/10.1016/s0022-3476(86)80222-0.

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39

MIWA, C., T. MANO, M. SAITO, S. IWASE, T. MATSUKAWA, Y. SUGIYAMA y K. KOGA. "Ageing reduces sympatho-suppressive response to head-out water immersion in humans". Acta Physiologica Scandinavica 158, n.º 1 (agosto de 1996): 15–20. http://dx.doi.org/10.1046/j.1365-201x.1996.527289000.x.

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40

Miki, K., M. M. Pazik, E. Krasney, S. K. Hong y J. A. Krasney. "Thoracic duct lymph flow during head-out water immersion in conscious dogs". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 252, n.º 4 (1 de abril de 1987): R782—R785. http://dx.doi.org/10.1152/ajpregu.1987.252.4.r782.

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Water immersion (WI) increases plasma volume in awake dogs. The contribution of lymph flow to this fluid shift was studied in six splenectomized conscious dogs with a side fistula of the thoracic duct. Lymph flow, hematocrit (Hct), and plasma (CP) and lymph (CL) protein concentration were measured during 60 min in air and 120 min of WI (37 degrees C). Lymph flow in air averaged 0.96 +/- 1.0 (SE) ml/min. Lymph flow tended to decrease immediately in WI and was maintained at a level averaging 0.66 ml/min. CP/CL did not change significantly, whereas Hct fell significantly by 1.51 +/- 0.2% (Hct units) at 40 min of WI. Urine flow increased significantly to a maximum value of 1.5 +/- 0.5 ml/min at 40-60 min of WI compared with a mean value in air of 0.3 +/- 0.1 ml/min. The Hct and urine flow responses indicate that fluid shifted into the intravascular space during WI. Since lymph flow tended to decrease, the fluid shift in WI occurs across the capillary wall and not via lymphatic channels.

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41

Johansen, L. B., N. Foldager, C. Stadeager, M. S. Kristensen, P. Bie, J. Warberg, M. Kamegai y P. Norsk. "Plasma volume, fluid shifts, and renal responses in humans during 12 h of head-out water immersion". Journal of Applied Physiology 73, n.º 2 (1 de agosto de 1992): 539–44. http://dx.doi.org/10.1152/jappl.1992.73.2.539.

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Changes in plasma volume (PV) throughout 12 h of thermoneutral (34.5 degrees C) water immersion (WI) were evaluated in eight subjects by an improved Evans blue (EB) technique and by measurements of hematocrit (Hct), hemoglobin (Hb), and plasma protein concentrations (Pprot). Appropriate time control studies (n = 6) showed no measurable change in PV. At 30 min of immersion, EB measurements demonstrated an increase in PV of 16 +/- 2% (457 +/- 70 ml). Calculations, however, based on concomitant changes in Hct, Hb, and Pprot showed an increase in PV of only 6.9 +/- 0.9 to 10.0 +/- 0.8% at 30 min of WI. PV values based on EB measurements subsequently declined throughout WI to (but not below) the preimmersion level. Concomitantly, changes in PV calculated from Pprot values remained increased, whereas estimations of changes in PV based on Hct and Hb values returned to prestudy levels after 4 h of immersion. It is concluded that PV initially increases by 16 +/- 2% during WI and does not decline below preimmersion and control levels during 12 h of immersion despite a loss of 0.9 +/- 0.2 liter of body fluid. Furthermore, changes in Hct, Hb, and Pprot do not provide accurate measures of the changes in PV during WI in humans.

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42

Watenpaugh, Donald E. "Analogs of microgravity: head-down tilt and water immersion". Journal of Applied Physiology 120, n.º 8 (15 de abril de 2016): 904–14. http://dx.doi.org/10.1152/japplphysiol.00986.2015.

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This article briefly reviews the fidelity of ground-based methods used to simulate human existence in weightlessness (spaceflight). These methods include horizontal bed rest (BR), head-down tilt bed rest (HDT), head-out water immersion (WI), and head-out dry immersion (DI; immersion with an impermeable elastic cloth barrier between subject and water). Among these, HDT has become by far the most commonly used method, especially for longer studies. DI is less common but well accepted for long-duration studies. Very few studies exist that attempt to validate a specific simulation mode against actual microgravity. Many fundamental physical, and thus physiological, differences exist between microgravity and our methods to simulate it, and between the different methods. Also, although weightlessness is the salient feature of spaceflight, several ancillary factors of space travel complicate Earth-based simulation. In spite of these discrepancies and complications, the analogs duplicate many responses to 0 G reasonably well. As we learn more about responses to microgravity and spaceflight, investigators will continue to fine-tune simulation methods to optimize accuracy and applicability.

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43

DIKSHIT, Mohan B., Mohammad FAHIM y P. Seshagiri RAO. "Atrial Type B Receptor Activity during Head-Out Water Immersion (HOWI) in Dogs." Japanese Journal of Physiology 44, n.º 6 (1994): 665–73. http://dx.doi.org/10.2170/jjphysiol.44.665.

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44

Barbosa, Tiago M., Maria F. Garrido y José Bragada. "Physiological Adaptations to Head-Out Aquatic Exercises With Different Levels of Body Immersion". Journal of Strength and Conditioning Research 21, n.º 4 (2007): 1255. http://dx.doi.org/10.1519/r-20896.1.

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45

Anderson, J. V., N. D. Millar, J. P. OʼHare, R. J. M. Corrall y S. R. Bloom. "Natriuresis of Head-Out Water Immersion Is Associated with ANP Release in Man". Journal of Cardiovascular Pharmacology 8, n.º 6 (noviembre de 1986): 1325. http://dx.doi.org/10.1097/00005344-198611000-00191.

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46

Wiens, Andrew D., Andrew M. Carek y Omer T. Inan. "Sternal vibrations during head-out immersion: A preliminary demonstration of underwater wearable ballistocardiography". Journal of the Acoustical Society of America 138, n.º 3 (septiembre de 2015): EL342—EL346. http://dx.doi.org/10.1121/1.4929613.

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47

Tajima, F., S. Sagawa, J. Iwamoto, K. Miki, B. J. Freund, J. R. Claybaugh y K. Shiraki. "Cardiovascular, renal, and endocrine responses in male quadriplegics during head-out water immersion". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, n.º 6 (1 de junio de 1990): R1424—R1430. http://dx.doi.org/10.1152/ajpregu.1990.258.6.r1424.

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The present study was undertaken to determine the relative influence of the action of the central nervous system on the mechanism of water-immersion-induced diuresis by comparing physiological responses of quadriplegic (QP) and normal subjects. After overnight fasting seven male QP subjects with complete cervical cord transections (C5-C8) and six normal men were tested before, during, and after 3 h of head-out immersion (HOI) in thermoneutral water (34.5-35.0 degrees C). The reversible increase in urine flow and the total urine volume (309 +/- 53 ml in 3 h) in QP subjects were comparable with that of the normal subjects (318 +/- 96 ml in 3 h). While osmolal excretion was increased in QP subjects, its magnitude was less when compared with that of normal subjects. Instead, the increased urine flow in QP subjects was characterized by increased glomerular filtration rate (GFR) and free water clearance, in contrast to a predominantly osmotic diuresis with no changes in GFR in the normal subjects. The HOI elevated (P less than 0.05) systolic pressure only in QP subjects, whereas the increase in cardiac output was the same in both groups. While plasma renin activity and aldosterone responses to HOI in QP subjects were comparable with those of normal individuals, plasma atrial natriuretic factor (ANF) in QP subjects was twofold higher (P less than 0.05) during HOI, and the approximately threefold increase in ANF (P less than 0.05) in QP subjects due to HOI was the same as that of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

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48

Al-Haidary, A. D., I. G. Mackay, K. D. Bhoola, N. D. Millar, M. L. Watson y J. C. Mackenzie. "Electrolyte and Humoral Responses of Renal Transplant Patients to Head-Out Water Immersion". Nephrology Dialysis Transplantation 5, n.º 7 (1 de enero de 1990): 535–41. http://dx.doi.org/10.1093/ndt/5.7.535.

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49

Fujisawa, Hiroyuki, Naoki Suenaga y Akio Minami. "Electromyographic study during isometric exercise of the shoulder in head-out water immersion". Journal of Shoulder and Elbow Surgery 7, n.º 5 (septiembre de 1998): 491–94. http://dx.doi.org/10.1016/s1058-2746(98)90200-2.

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50

Vogelaere, P., G. Deklunder y J. Lecroart. "Cardiac output variations in supine resting subjects during head-out cold water immersion". International Journal of Biometeorology 39, n.º 1 (marzo de 1995): 40–45. http://dx.doi.org/10.1007/bf01320892.

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