Abstract 404: Racial Differences In Aldosterone And Its Relationship With Potassium
Potassium (K), acting synergistically with angiotensin-II, stimulates aldosterone production, which then promotes secretion of K in distal nephron. Blacks have on average significantly lower aldosterone levels than whites. The extent to which the reduced aldosterone level stems from less stimulation by K is unknown. Also, there may be less dependency on aldosterone to influence K homeostasis in blacks. In an observation study, we looked for race differences in K-aldosterone relationships in a cohort of healthy young blacks and whites (ages 5-39 years). We analyzed 1116 samples from 161 blacks and 271 whites. Our data showed that at although K decreased with age (at a rate of 0.09 mmol/L per year), at any given age K levels of blacks and whites were quite similar (Fig a & b), whereas plasma aldosterone levels were approximately 7 ng/dL lower in blacks (p<0.0001; Fig c & d). We then assessed the aldosterone-K relationships by characterizing the effects of K on aldosterone as functions of age. K and aldosterone were positively correlated in both race groups (p<0.0001), an effect that declined with age for both groups (p<0.05), but at any given age K effect was significantly greater in whites (p<0.001; Fig e and f). Blacks maintained K at a level that was nearly identical to whites despite their having much lower aldosterone levels. We speculate that an expanded volume in blacks facilitated K excretion and reduced stimulation of aldosterone by K because of less synergism with angiotensin II. With increasing age additional sodium may accumulate which increases volume resulting in concurrent declines in K, aldosterone, as well as their associations, in both race groups.
Author Disclosures: W. Tu: None. G. Eckert: None. J. Pratt: None.
- © 2014 by American Heart Association, Inc.