Dual Effects on the Sphincter of Oddi and Gallbladder Induced by Stimulation of the Right Great Splanchnic Nerve

The right great splanchnic nerve was stimulated in 15 anesthetized cats. Effects on gallbladder pressure, resistance to flow through the sphincter of Oddi, and (in 6 cats) intramural duodenal pressure were evaluated. By nerve stimulation, the sphincter was consistently contracted and the intestine relaxed. The gallbladder showed variable slight responses, except in 3 cats where consistent relaxation was obtained. Cholecystokinin (i.v.) relaxed the sphincter and contracted the gallbladder. During the action of the hormone, the nervous response was counteracted in the sphincter; in the gallbladder, relaxation was obtained in all cats. Noradrenaline (i.v.) mimicked the responses induced by adrenergic nerve stimulation. The contraction of the sphincter induced by nerve stimulation and by noradrenaline was inhibited by phenoxybenz‐amine and atropine. The relaxation of the gallbladder was prevented by propranolol. It is concluded that the adrenergic splanchnic nerves, as well as i.v. noradrenaline, mainly activated α‐receptors in the sphincter of Oddi (inducing contraction) and β‐receptors in the gallbladder (inducing relaxation). Results obtained with the nerve stimulation and the 3 blocking agents also confirmed the presence of contraction‐mediating atropine‐sensitive cholinoceptors in the sphincter and the gallbladder, contraction‐mediating α‐receptors in the gallbladder, and relaxation‐mediating β‐receptors in the sphincter.