A periarterial nerve-circular muscle preparation from the caecum of the guinea-pig

Abstract

Abstract A periarterial nerve-circular muscle preparation from the caecum of the guinea-pig has been described. Stimulation of the periarterial nerve produced relaxation of the circular muscle strip. These responses were blocked by adrenergic neurone blocking agents but not by ganglion blocking drugs. Phenoxybenzamine or piperoxan greatly reduced the relaxation but propranolol abolished it. No relaxation was observed on preparations from animals pre-treated with reserpine. It was observed that after the blockade of the responses to periarterial nerve by adrenergic neurone blocking drugs, stimulation of the periarterial nerves in the presence of physostigmine induced contractions which were blocked by local anaesthetics or hyoscine but not consistently by ganglion blocking drugs.