Studies on the Ganglionic Site of Action of Sympathetic Outflow to the Stomach



In acute experiments on cats anesthetized with chloralose, inhibition of excitatory vagal responses of gastric smooth muscle was produced by reflex or direct activation of an adrenergic nerve fibre system. The reflex that could be elicited by distension of a jejunal loop or stimulation of mesenteric afferents was dependent on intact spinal connections because it was blocked by spinal anesthesia. Activation of the adrenergic nerve fibre system did not inhibit gastric myogenic tone or gastric muscle contraction elicited by the muscarinic action of acetylcholine. It was therefore concluded that the adrenergic outflow responsible for this type of inhibition acts on parasympathetic intramural ganglion cells involved in the excitatory control of gastric motility.