Effects of ?-bungarotoxin on acetylcholine-induced response at the Helix neuronal membrane

Abstract

The effects of α-bungarotoxin (α-BT) on two patterns of acetylcholine (ACh)-induced response differing in desensitization rate were investigated in isolated mollusk neurons using intracellular dialysis and concentration clamping techniques. It was found that α-BT depressed both types of ACh-induced response — a reversible action in the majority of experiments performed. It also exerted a blocking effect on ACh-induced currents dependent on the presence of albumin, although albumin itself produced no noticeable change in ACh-induced response. Concentration dependence of α-BT-induced blockade on both types of currents evoked by 1 and 10 µM ACh was investigated. The α-BT concentrations producing a 50% suppression of the current evoked by 1 µM ACh were calculated by approximating concentration plots as (13.85±1.25)×10−9 and (5.56±1.0)×10−8 g/ml for type A and B cells respectively.