Our previous work on aldosterone secretion suggested that dihydropyridine-sensitive calcium channels, one type of voltage-dependent calcium channels (VDCC), are functionally impaired in adrenal capsule preparations from the pregnant rat. The aim of this study was to determine whether, during pregnancy, the density and/or activity of these channels is altered in the adrenal zona glomerulosa. These VDCC measured with [³H]nitrendipine binding were not different between membrane preparations of nonpregnant and pregnant rats. Western blots were performed using two different antibodies, a polyclonal (PcAb) directed against the ₁-subunit of VDCC and a monoclonal (McAb) that recognizes an intracellular domain of that protein. McAb immunoreactivity showed a significant decrease in preparations from pregnant rats, whereas no difference was observed with PcAb. VDCC activity was estimated by ⁴⁵Ca²⁺ uptake in isolated adrenal cortex and by intracellular calcium concentration ([Ca²⁺]_i) in adrenal glomerulosa cells with the Ca²⁺ probe fura PE3. These measurements revealed that KCl stimulation produced greater Ca²⁺ influx in nonpregnant than in pregnant rats. Nifedipine (a blocker of VDCC) inhibited this stimulation only in nonpregnant rats, whereas BAY K 8644 (an activator of VDCC) increased Ca²⁺ influx in pregnant rats only. These data suggest that, during pregnancy, the altered regulation of calcium homeostasis in adrenal glomerulosa is linked to a conformational alteration of VDCC.