Captopril administration in sodium-restricted subjects reduced angiotensin II (from 31 to 13 pg/ml) and aldosterone (from 25 to 7 ng/dl) to values similar to those on high sodium intake.
Does captopril reduce plasma aldosterone and angiotensin II levels in sodium-restricted normal subjects?
Captopril completely suppresses sodium-restricted levels of angiotensin II and aldosterone, supporting the renin-angiotensin system as the primary mediator of the adrenal response to sodium restriction.
The primacy of angiotensin II as the mediator of the adrenal's response to sodium restriction is controversial. We administered the oral converting enzyme inhibitor, captopril (SQ 14225), to test whether reduction of angiotension II generation for 26 h in sodium-restricted subjects would lower plasma aldosterone levels to values observed in subjects on a high sodium intake. Accordingly, plasma angiotensin II and aldosterone levels were measured in nine recumbent normal subjects on high (200 meq) and low (10 meq) sodium intakes and low sodium intake with captopril (12.5--25 mg four times a day for 26 h). Captopril reduced the sodium-restricted angiotensin II levels from 31 +/- 6 to 13 +/- 2 pg/ml, which was indistinguishable from that measured on the high sodium intake (11 +/- 2 pg/ml). Concomitantly, aldosterone levels were reduced from 25 +/- 4 to 7 +/- 1 ng/dl, which was similar to the high sodium value (8 +/- 1 ng/dl). There were no significant changes in serum sodium, cortisol, or potassium at the three sampling times. Thus, the complete suppression of the sodium-restricted levels of both angiotensin II and aldosterone into the high sodium range by captopril provides strong support for the hypothesis that the renin-angiotensin system is the prime mediator of the adrenal's response to sodium restriction.
Swartz et al. (Sun,) conducted a other in Normal subjects (n=9). Captopril vs. High sodium intake and low sodium intake without captopril was evaluated on Plasma angiotensin II and aldosterone levels. Captopril administration in sodium-restricted subjects reduced angiotensin II (from 31 to 13 pg/ml) and aldosterone (from 25 to 7 ng/dl) to values similar to those on high sodium intake.