Renin and aldosterone in the cardiomyopathic hamster in congestive heart failure.

The renin-aldosterone system was studied in cardiomyopathic hamsters (CMH) before and after the onset of untreated clinical congestive heart failure. Age-matched random-bred hamsters (RB) served as controls. Before heart failure, there were no differences in body weight accretion, sodium balance, plasma renin activity or in vitro aldosterone production. After the onset of heart failure in CMH, body weight increased at a greater rate than in RB and positive sodium balance was nearly twice control levels. Although plasma renin activity was greater (P less than 0.005) in CMH than in RB (23.4+/-4.2 (mean+/-SEM) vs. 3.8+/-1.8 ng/ml/h), aldosterone production (101+/-15 vs. 95+/-16 ng/h) did not differ. Plasma aldosterone was low or undetectable in RB and in CMH in heart failure. In response to angiotensin stimulation, aldosterone production increased in both strains and did not differ. No difference in muscle potassium content, potassium balance or excretion was detected. Thus, in CMH, congestive heart failure is attended by increased plasma renin activity without a significant increase in aldosterone production, a dissociation which does not appear to be due to adrenal unresponsiveness to angiotensin II or to potassium depletion.