The role of calcium in the control of renin release.

The effects on in vitro renin release from rat kidney cortex of various agents which are thought to alter intracellular Ca were investigated. Incubation in Ca-free medium had no effect on basal or isoprenaline-stimulated renin release, but the addition of EDTA stimulated renin release. Angiotensin II (ANG II) and ouabain both inhibited basal and isoprenaline-stimulated renin release, and external Ca was important in this effect. Verapamil reduced the fall in basal renin release and the inhibitory effect of ANG II. In addition, verapamil blocked the inhibition by ANG II, but not by ouabain, of isoprenaline-stimulated renin release. Isoprenaline may stimulate the Na,K-ATPase leading to increased Ca efflux via Na-Ca exchange, whereas ouabain may have the opposite effect. ANG II probably stimulates Ca influx and release from intracellular stores.