BAY K 8644, a calcium channel agonist, inhibits renin secretion in vitro

These experiments were designed to characterize the renin secretory effects of BAY K 8644, a dihydropyridine derivative which acts as a Ca channel agonist. The rat renal cortical slice preparation was used. BAY K 8644 produced a concentration-dependent inhibition of basal renin secretion. Although the inhibitory effect was not blocked by nifedipine or by methoxyverapamil in concentrations which effectively block the renin secretory effects of K-depolarization, higher concentrations did block. Moreover, chelating extracellular Ca2+ with EGTA also blocked the inhibitory effect. These observations are consistent with the hypothesis that the inhibitory effect is mediated by Ca2+ influx. Collectively, the results add to the growing evidence that Ca2+ is an inhibitory second messenger in the renin secretory process.