Biphasic alteration of renin release by calcium.

The effects of calcium reintroduction on renin release were examined. Calcium reintroduction to calcium-deprived rat renal cortical slices caused an initial stimulation of renin release (30-40 min) followed by a period of suppression of release (4.5 hr). With ouabain present the initial stimulation was enhanced but the subsequent fall in release was more pronounced. Our results suggest that although renin release from juxtaglomerular cells can be both stimulated and inhibited by raising intracellular calcium, it is the inhibition of release that is the more persistent effect.