Calcium and the Control of Renin Release from Human Chorion

Abstract

Sections of human chorion were perfused with a bicarbonate buffer for five hours. Samples were collected every 20 minutes and the concentration of active and total renin in the perfusate was determined by radioimmunoassay. Active and total renin secretion was not affected when the chorion was perfused with the ionophore Br-X537A (6.4-32.μmol/L) or with a calcium-free solution. However, if the latter contained Br-X537A (6.4 and 16.1 μmol/L) the release of total renin was enhanced whilst that of active renin did not change. Thus, perfusion of chorion with a calcium-free buffer containing an ionophore stimulates the secretion of inactive renin.