The action of cholinomimetic and cholinolytic agents, hemicholinium-3 and α- and β-bungarotoxin on the body wall muscle of the earthworm, lumbricus terrestris

Abstract

Strips of muscle, approximately 12 segments in length, were prepared from the body wall of the earthworm, Lumbricus terrestris, from which the nerve cord and viscera had been removed. Contractions to electrical stimulation and acetylcholine agonists were recorded using an isometric transducer. A range of nicotinic and muscarinic agonists and antagonists were tested on this preparation and the results indicate that the acetylcholine receptor on this muscle cannot be classified as either nicotinic or muscarinic. Hemicholinium-3 abolished electrically induced muscle twitches at concentrations which had no effect on the acetylcholine response. α-Bungarotoxin blocked the responses to both electrical stimulation and acetylcholine while β-bungarotoxin blocked the contractions induced by electrical stimulation but potentiated the acetylcholine contraction.