Abstract 400: Blood Pressure Effect Of Aldosterone Increased With Age

Abstract

Aldosterone often plays a central role in the regulation of blood pressure (BP) by acting on the distal nephron to promote sodium and water retention. As people age, levels of aldosterone and renin tend to decrease. It is unclear how these changes affect BP. To investigate, we examined the temporal changes in plasma aldosterone concentration (PAC) and plasma renin activity (PRA) in a cohort of healthy blacks and whites (ages: 7 - 38 years). We examined the relationship between PAC and BP at different ages. Our data showed that while blacks on average had lower PRA levels than whites at any given age (p<0.0001), PRA decreased with age (p<0.0001) in both race groups. PAC also decreased with age (p<0.0001) but decline was faster whites. Aldosterone-renin ratio (ARR), on the other hand, increased with age in both race groups. PAC effects on SBP in blacks and whites were estimated and presented graphically (Figure 1). The figure showed that aldosterone effect on BP increased with age in blacks and whites (p<0.008); but at any given age, the BP effect of PAC was greater in blacks than in whites, and this racial difference became more pronounced with an increase in age. In conclusion, BP becomes more sensitive to aldosterone with age. An accumulated sodium load with volume expansion may sensitize BP to even small increment of aldosterone. Blacks appear to be especially vulnerable to such an increased level of sensitivity.