The stimulation of aldosterone secretion from adrenal glomerulosa cells by angiotensin II (All), potassium, and ACTH is highly dependent on the extracellular calcium concentration. To evaluate the role of voltage-dependent calcium channels in aldosterone production, we analyzed the actions and binding of calcium channel antagonists in collagenase-dispersed adrenal glomerulosa cells and membrane-rich particles. In rat glomerulosa cells, nifedipine caused dose-dependent inhibition of the aldosterone responses to All and potassium, with halfmaximum inhibitory concentration (IC₅₀) of 100 nm, but had no effect on ACTH or 8-bromo-cAMP stimulated steroidogenesis in adrenal glomerulosa and fasciculata cells. Binding studies with [³H]nitrendipine in adrenal glomerulosa cells revealed a high affinity site with dissociation constant (K_d) of 0.4 ± 0.1 nm, similar to that described in other tissues but about 100-fold lower than the IC₅₀ for blockade of aldosterone production. However, Scatchard analysis of binding data from three of seven experiments in isolated adrenal glomerulosa cells revealed a low affinity site with K_d of 130 nm, in agreement with the ICso for the effect of nifedipine on aldosterone production. In rat adrenal particles, nitrendipine-binding sites were located in the adrenal capsule and medulla and were undetectable in the zona fasciculata. Furthermore, there was a close correlation (r = 0.92) between the concentrations of nitrendipine-binding sites and All receptors in the different zones of the adrenal in rat, dog, and cow, suggesting a functional relationship between All receptors and calcium channels. These studies have shown a major and selective role of voltage-dependent calcium channels in the control of aldosterone secretion by the major physiological regulators, All and potassium. (Endocrinology118: 112–118, 1986)