The mechanisms of renal tubular dysfunction in old age have been examined in twenty-eight clinically healthy elderly subjects without infection, and in fourteen subjects of similar age with laboratory evidence of intrarenal infection. The data were compared with those from thirteen clinically healthy young subjects. Studied were: proximal tubular (Tm(PAH)) and distal tubular (CH2O) activity, [...]
No abstract available.
The effect of age on the hypothalamic-hypophyseal-renal axis in normal man was determined by assaying plasma arginine vasopressin (AVP) responses to inhibitory and to secretory stimuli. Nine young (21-49 years) and 13 old (54-92 years) subjects received IV ethanol (375 mg/m2 per min). AVP levels fell progressively during the infusion in the young group, but [...]
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 [...]
No abstract available.
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 [...]
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 [...]
Dehydration is a common clinical syndrome associated with many illnesses and treatments in the elderly. Prior studies have shown diminished sensation of thirst during water deprivation. It is currently unclear whether age-related decreases in thirst perception impair the defense against a hyperosmolar challenge. To examine the impact of water ingestion during hyperosmolality, young and old [...]
A trend toward more hot and humid summers in the United States raises concern for the health of our elderly population. Older adults are more vulnerable to heat illness than younger people because of dysfunctional thermoregulatory mechanisms, chronic dehydration, medications, and diseases involving the systems that regulate body temperature. Heat exhaustion, if untreated, will lead [...]