Plasma Levels of Prorenin and Renin in Blacks and Whites: Their Relative Abundance and Associations With Plasma Aldosterone Concentration

BACKGROUND: All renin arises from prorenin. The proportion of renin relative to prorenin could influence overall renin-angiotensin-aldosterone activity. We sought to determine whether prorenin levels were related to extracellular volume, as reflected by the levels of plasma renin activity (PRA), and to aldosterone. METHODS: We analyzed plasma levels of prorenin, renin, and aldosterone, as well as their interactions, in 129 young blacks and whites. RESULTS: Blacks had lower plasma renin concentration (PRC) and PRA, but had prorenin levels similar to whites (69 pg/ml in blacks vs. 62 pg/ml in whites, P = 0.41). As a result, the renin-to-total renin ratio was significantly lower in blacks (11.5% in blacks as compared to 19.8% in whites; P = 0.0001). Because prorenin also resides in tissues including the adrenal where it can bind to a specific receptor to generate angiotensin II, we examined the relationship of prorenin levels to plasma aldosterone concentrations (PAC). While a positive association between PRC and PAC was found in both blacks and whites, PAC was positively related to prorenin in whites (P = 0.04) but negatively in blacks, an observation that we hypothesize was due to reduced prorenin-to-renin conversion in blacks. CONCLUSIONS: We observed a disproportionately high level of prorenin in blacks. These high circulating prorenin levels however do not result in greater adrenal angiotensin II and aldosterone production in healthy young blacks.