title: Effect of prolonged exercise at altitude on the renin-aldosterone system.
abstract: The combined effect of exercise and altitude on the renin-aldosterone system was studied in six male subjects on a fixed diet. After 4 control days at rest and at low altitude, subjects ascended to 3,100 m and took about 7 h exercise daily for 5 days. There followed a 4-day recovery period at low altitude. Daily blood samples were taken for estimation of plasma renin activity (PRA), plasma aldosterone concentration (PAC), and angiotensin converting-enzyme (ACE) activity. Results showed a maximal rise in PRA and PAC with exercise at altitude maximal on the first 2 days. ACE activity fell by 23% at altitude. Compared with similar exercise at sea level, the rise in PAC was comparable but the rise in PRA was four times greater, indicating a marked decrease in PAC response to PRA. It is suggested that this loss of sensitivity of PAC to PRA is mediated by the measured reduction in ACE activity.
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood; D000531:Altitude; D006801:Humans; D008297:Male; D008875:Middle Aged; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D005082:Physical Exertion; D011187:Posture; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System; D013997:Time Factors
chemical_list: D000450:Aldosterone; D007703:Peptidyl-Dipeptidase A; D012083:Renin