Pharmacological Investigation of the Nature of the Innervation of the Muscles of Helix Aspersa

Abstract

ABSTRACT Bacq (1947) has reviewed the known actions of autonomic effector substances on invertebrates. Concerning the muscles of snails relatively little is known. Boyer (1926) showed that adrenaline had no effect on the contraction of the ventricular muscle of Helix pomatia in a concentration of less than 1 in 20,000, but that higher concentrations slowed the heart and produced irregularities of rhythm. Very high concentrations (1 in 250) arrested the heart beat. According to Jullien (1936) the ventricle of the same snail is sensitive to acetylcholine in a concentration of 1 part per million. There seems to be little other information available, other than the general statements of Bacq (1947) that in many Molluscs physostigmine (eserine) fails to potentiate the effects of acetylcholine, that in Cephalopods curare, but not atropine, abolishes the effect of stimulating the vesical nerve, and that in Molluscs as a whole the muscles of locomotion do not appear to be cholinergic in type. In the common English snail, Helix aspersa, a portion of the alimentary canal (crop and rectum), or of the heart (ventricle), or the columellar muscle (which retracts the main part of the snail within its shell) was isolated, and the effects of drugs upon it examined, with the aim of determining the nature of the neurohormonal mechanism involved in contraction.