An examination of nerve‐mediated, hyoscine‐resistant excitation of the guinea‐pig colon

Abstract

1. The mechanical and electrical activity of the smooth muscle of the distal colon of the guinea‐pig has been recorded in experiments designed to determine the nature of the nerve‐mediated excitation of the muscle. 2. The spontaneous contractions of the colon, normally observed in vitro, were similarly antagonized by hyoscine or tetrodotoxin. However, neither drug caused complete cessation of the spontaneous activity. 3. The contractile responses of the colon to repetitive stimulation of intramural nerve fibres were of two types, a primary contraction which occurred within 1 sec of the beginning of stimulation and a secondary contraction which occurred after stimulation. The primary contract..