The cell-attached recording mode of the patch-clamp technique was used to study Ca²⁺ permeable background currents of glomerulosa cells from rat and bovine adrenal gland. With a pipette filled with 110 mm BaCl₂ or 90 mM CaCl₂, three different types of unitary currents were detected. The B₁ channel demonstrates a nonlinear I-V curve. The conductances are 4 and 7 pS at -40 and -70 mV, respectively. The curve of the opening probability vs. membrane potential is bell shaped with its maximum at -70 mV. The B₂ channel has a conductance of 6 pS, while the B₃ channel shows a nonlinear I-V relationship with conductances close to 17 and 10 pS at HPs of -60 and -20 mV. The three types of currents are insensitive to dihydropyridines.

We suggest that these background currents could be responsible for the basal calcium influx and aldosterone secretion previously observed in nonstimulated glomerulosa cells.