Age and hypohydration independently influence the peripheral vascular response to heat stress
| Autor: | N. L. Turner, W. L. Kenney, D. L. Newswanger, D. E. Hyde, S. M. Puhl, Clarke G. Tankersley |
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| Rok vydání: | 1990 |
| Předmět: |
Adult
Male medicine.medical_specialty Aging Hot Temperature Physiology Hemodynamics Animal science Stress Physiological Physiology (medical) medicine Humans Relative humidity Skin Dehydration Chemistry VO2 max Blood flow Thermoregulation Middle Aged Surgery Plasma osmolality Vasodilation medicine.anatomical_structure Blood pressure Regional Blood Flow Vascular resistance Body Temperature Regulation |
| Zdroj: | Journal of applied physiology (Bethesda, Md. : 1985). 68(5) |
| ISSN: | 8750-7587 |
| Popis: | Seven young (Y, 22-28 yr) and seven middle-aged (MA, 49-60 yr) normotensive men of similar body size, fatness, and maximal oxygen uptake (VO2max) were exposed to a heat challenge in an environmental chamber (48 degrees C, 15% relative humidity). Tests were performed in two hydration states: hydrated (H, 25 ml water/kg body wt 1 h before the test, 2.5 h before exercise) and hypohydrated (Hypo, after 18-20 h of water deprivation). Each test began with a 90-min rest period during which the transiently increased plasma volume and decreased osmolality after drinking in the H condition returned to base line. This period was followed by 30 min of cycle exercise at a mean intensity of 43% VO2max and a 60-min resting recovery period with water ad libitum. Although prior drinking caused no sustained changes in plasma osmolality, Hypo increased plasma osmolality by 7-10 mosmol/kg in both groups. There were no significant age differences in water intake, urine output or osmolality, overall change in body weight, or sweating rate. In the H state, the percent change in plasma volume was less (P less than 0.01) during exercise for the Y group (-5.9 +/- 0.7%) than for the MA group (-9.4 +/- 0.6%). Esophageal temperature (Tes) was higher in the Hypo condition for both groups with no age-related differences. Throughout the 3-h period, mean skin temperature was higher in the Y group and significantly so (P less than 0.05) in the Hypo condition.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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