Abstract
Plasma renin activity (PRA), serum angiotensin-converting enzyme (ACE) activity, and plasma aldosterone concentration (PAC) were measured in 15 subjects at sea level and at high altitude. Previous work has shown that on first ascent to altitude PAC and ACE are reduced, whereas PRA may be raised or reduced. After 2-4 wk at 6,300 m all hormones had returned to within +/- 10% of sea-level values. In seven subjects PRA and PAC were measured when exercise stopped. PRA and PAC were both elevated, PRA more than PAC; i.e., the PAC response to PRA was markedly blunted. Since ACE activity was normal, it is suggested that there may be down regulation, i.e., reduction in density of angiotensin II receptors on the adrenal cortex and/or induction of enzymes which degrade angiotensin II. This mechanism apparently protects the subjects from very high levels of PAC and sodium retention when hypoxia and exercise raise PRA to very high levels.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
