CARTAP MODULATION OF THE NICOTINIC ACETYLCHOLINE RECEPTOR-CHANNEL OF CLONAL RAT PHEOCHROMOCYTOMA (PC12) CELLS

Cartap, the synthetic analog of nereistoxin, is known to act on the ni cotinic acetylcholine receptor-channel (AChR). Effects of cartap on th e neuronal nicotinic AChR of clonal rat phaeochromocytoma (PC 12) cell s were studied using a single-channel patch clamp method. When cartap was co-applied with acetylcholine, the single-channel openings were sh ortened and occurred in bursts separated by brief closures or gaps. Th e current amplitudes in the presence of cartap were virtually identica l to those of currents induced by ACh only. Mean open time and burst d uration were significantly decreased in the presence of cartap in a do se-dependent manner. These changes of single-channel kinetics result i n a significant decrease in total charge carried through the open AChR explaining the suppressive effect of cartap on nicotinic AChR. Result s suggest that cartap could act as an open channel blocker at the nico tinic AChR.