Calmodulin-independent stimulation of renin release by exposure of rat kidney cortical slices to calcium.

1. Effects of calcium-interacting agents on the calcium-induced stimulation of renin release from kidney cortical slices pretreated with calcium-free medium were examined. 2. The exposure of calcium to the slices pretreated with calcium-free medium enhanced the release of renin, followed by a decreased response in the release. The amount of lactate dehydrogenase released from the slices did not correlate with that of renin. 3. High potassium depolarization significantly potentiated the decreased response of renin release, with no influence on the stimulation of the release by exposure to calcium. 4. The decrease in renin release was attenuated by calcium-interacting agents, such as nifedipine, TMB-8 and W-7, but these agents were without effect on the stimulation of the release by exposure to calcium. 5. Thus, the calcium-calmodulin system apparently is not involved in the increased response of renin release following exposure to calcium.