Reflex Sympathetic Inhibition of Colonic Motility in the Cat

Sympathico-adrenergic mechanisms involved in the reflex inhibition of colonic motility were investigated in anaesthetized cats. Reflex inhibition of spontaneous motility of the colon was induced by application of hydrochloric acid onto the serosal surface of the small intestine and the peritoneum of the abdominal wall. This inhibition was reduced by propranolol and phentolamine. The spontaneous colonic motility was also reduced by administration of isoproterenol, noradrenaline, and clonidine. It is concluded that the sympathetic reflex inhibition of colonic motility is mediated by alpha- and beta-adrenergic mechanisms in the cat.