Three types of acetylcholine-induced single channel currents in clonal rat pheochromocytoma cells

Single channel currents induced by acetylcholine were recorded from nerve growth factor-differentiated clonal rat pheochromocytoma (PC12) cells by using the patch-clamp technique. Inward current amplitudes were heterogeneous and could be related to three classes of unitary current. The three current-voltage relations were linear for patch membrane potentials ranging from -50 mV to -120 mV. At 22 degrees C, conductances of 22 pS, 31 pS and 39 pS were obtained. The extrapolated reversal potential for the channels was 0 mV and the mean open time approximately 10-20 ms. These results may indicate that PC12 cells possess three types of acetylcholine receptor channels.