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 [...]
A time-related, heat stress tolerance curve for unimpaired mental performance was constructed by Wing from a summary of 15 studies. The tolerance limits, more properly described as the lower limits for heat impaired mental performance, were subsequently adopted by the National Institute for Occupational Safety and Health as the recommended standard of tolerance times for [...]
Salivary glands require body fluids for normal function. It has been suggested that decreased levels of hydration (dehydration) may cause diminished salivary output, but it is not known whether salivary flow rates are related to biological measures of hydration status. The purpose of this study was to determine whether reduced parotid salivary flow rates, as [...]
No abstract available.
1. Nine normal subjects (eight male, one female) on a fixed daily intake of 150 mmol of sodium and 80 mmol of potassium, were randomized to receive either 3 days of 1.0 litre total water intake/24 h (food + fluid) or 4 days of 6.8 litres total water intake/24 h, and were then crossed over [...]
The tubular handling of sodium in two groups of healthy old people, under the action of indomethacin and aldosterone was studied. Urinary aldosterone elimination was measured. From the results obtained, it is deduced that the elderly lose sodium through incompetence of the distal nephron. The possibility is put forward of a Na-K-ATPase deficit and/or interstitial [...]
No abstract available.
We examined osmotic control of thirst and free water clearance in healthy older (65+, n = 10) and younger (Y, n = 6) subjects during a 3-h rehydration period after an approximately 2.4% decrease in body weight. Plasma volume (PV), plasma osmolality (Posm), renal function, and thirst were measured before and after dehydration and during [...]