PHYSOSTIGMINE BLOCKED NICOTINIC ACETYLCHOLINE-RECEPTORS IN RAT SYMPATHETIC-GANGLION NEURONS

ATM: To study the blocking mechanism of physostigmine (Phy) on nicotin ic acetylcholine receptors (NAChR) in sympathetic neurons. METHODS: Th e whole-cell patch-clamp technique was used to observe the effects of Phy on NAChR in the cultured sympathetic neurons from neonatal rat sup erior cervical ganglia (SCG). RESULTS: Phy 5 - 20 mu mol . L-1 inhibit ed neuronal NAChR in a concentration-dependent manner and accelerated the desensitization of NAChR. Changing the membrane potential from -50 to -90 mV did not affect the blocking effect of Phy. Phy 200 mu mol . L-1 did not induce any noticeable response in SCG neurons. CONCLUSION : Phy blocked NAChR in the sympathetic ganglion neurons by interacting with the allosteric sites out of the binding sites and the open ionic channels of the receptors. Phy did not possess excitative effect on N AChR in SCG neurons.