Bradykinin inhibits a potassium M-like current in rat pheochromocytoma PC12 cells.

We studied the action of bradykinin (BK) on ionic currents in fused pheochromocytoma PC12 cells under voltage-clamp in whole-cell mode, and on intracellular calcium using fura-2 BK induced the development of an outward current associated with an increase in intracellular calcium, followed by inhibition of an M-like current. The outward current was blocked by (+)-tubocurarine, and prevented when the calcium BAPTA or high concentrations of inositol 1,4,5-triphosphate were introduced into the cell, whereas the M-like current and its inhibition by BK remained unaffected. The protein kinase activator phorbol 12,13 dibutyrate partially reduced the M-current. M-current density did not substantially change after prolonged treatment with nerve growth factor.