The visceral nervous system of the earthworm II. Evidence of chemical transmission and the action of sympatheticomimetic and parasympatheticomimetic drugs on the tone of the alimentary canal

Abstract

Abstract The action of adrenaline, ephedrine, tyramine and acetylcholine on the tone of the alimentary canal of the earthworm is considered in relation to the effects of nerve stimulation described in a previous paper. The similarity between the effect of the drugs and nerve action indicates that the antagonistic groups of nerves which indirectly influence the tone of the gut are probably oholinergic and adrenergic. The indication of cholinergic nerves is confirmed by further, more direct, experimental evidence. The remarkable similarity which has been shown to exist between the type of indirect control of the gut in the earthworm and vertebrates is thus extended. The results of the experiments are considered in relation to those described by workers on other Invertebrates, and significant indications of a type of chemical transmission in earthworm remarkable in its similarity to that seen in vertebrates are described.