THE POTENTIATION BY ANTICHOLINESTERASE DRUGS OF THE RESPONSES OF THE GUINEA‐PIG ISOLATED VAS DEFERENS TO ALTERNATE PREGANGLIONIC AND POSTGANGLIONIC STIMULATION

Abstract

The potentiating effects of anticholinesterase drugs on the responses of the guinea-pig isolated vas deferens to electrical stimulation of the hypogastric nerve have been reported several times in recent years (Boyd, Chang & Rand, 1960; Burn & Weetman, 1963; Ohlin & Stromblad, 1963; Della Bella, Benelli & Gandini, 1964). It has now been established that most of the fibres in the hypogastric nerve are preganglionic (Sjostrand, 1962; Bentley & Sabine, 1963 ; Kuriyama, 1963; Ohlin & Stromblad, 1963; Birmingham & Wilson, 1963) so that when considering the possible sites at which the potentiating effect is exerted, the effects of inhibiting cholinesterase in the ganglion must be taken into account. The feasibility of stimulating preganglionic sr postganglionic nerve fibres in the guinea-pig isolated vas deferens was reported by Birmingham & Wilson (1963). It has therefore been possible to re-examine the effects of physostigmine and to describe the effects of diisopropylphosphorofluoridate (dyflos) on the isolated vas deferens stimulated alternately preganglionically and postganglionically. This paper describes the results of experiments which attempt to distinguish the sites of the potentiating effect of the anticholinesterase drug. Some of these results were reported to the July, 1964, meeting of the British Pharmacological Society at Bristol.