Molecular variations in the calcium-sensing receptor in relation to sodium balance and presence of hypertension in blacks and whites

Sodium (Na) excretion is to an extent tied to calcium (Ca) excretion; increases in Ca result in increased Na excretion. We hypothesized that molecular variation in the calcium-sensing receptor (CaSR), which imparts certain of the influences of extracellular Ca, might be related to differences in Na balance and blood pressure. We further hypothesized that such an influence by CaSR is more pronounced in blacks than in whites, as the hypertension in blacks appears to be more dependent on Na retention. Three common molecular variants in CaSR were studied. Two were more frequent in the whites (A986S, P< .0001, and G990R, P= .093), whereas Q1011E was more frequent in the blacks (P< .0001). Two distinctly separate groups were studied: (1) healthy schoolchildren in whom levels of the renin-aldosterone axis and blood pressure were measured, and (2) normotensive and hypertensive adults. Studies of association were made separately in the whites and the blacks. No association of any of the variants with Na balance (as estimated from renin and aldosterone levels) was observed. In the black schoolchildren, Q1011E showed a marginal association with a higher blood pressure (P= .093 for systolic and P= .025 for diastolic), a relationship that was considered to be nonsignificant after adjusting for multiple comparisons. Nor was there a significant association of the variants with presence or absence of hypertension. In summary, studies of two cohorts that included whites and blacks did not suggest that molecular variations in the CaSR influence either Na balance or blood pressure.