Characteristics of the acetylcholine‐operated channel at twitch and slow fibre neuromuscular junctions of the garter snake.

• DOI: 10.1113/jphysiol.1981.sp013541
• Publication Date: 2014-12-19T07:17:08Z
• Authors: V E Dionne; R L Parsons
• Keywords: Tetrodotoxin; Fast twitch muscle; Reversal potential

1. Synaptic responses to acetylcholine were recorded from garter snake (sp. Thamnophis) neuromuscular junctions with the voltage clamp. 2. In following respects identical in twitch and slow fibres: exponential miniature end‐plate current decay, reversal potential (approximately ‐5 mV), permeant ionic species (Na+, K+, Ca2+, but not Cl‐), two component decay presence of procaine, insensitivity tetrodotoxin, alpha‐bungarotoxin leiurus toxin. 3. The differed several important ways: rate was only half as sensitive at fibre end‐plates twitch; while all fluctuation spectra single component, about 60% not. latter could be fitted Lorentzian components. cases mean proportional total induced noise variance. 4. Two mechanisms which might account for response differences identified tested a fashion independent specific molecular kinetics. different do arise separate ion‐selective channels ions seem unlikely derive populations synaptic extrasynaptic channels.