Adrenergic and Cholinergic Innervation of the Rat Urinary Bladder

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Abstract
The autonomic innervation of the rat urinary bladder was studied using histochemical methods and nerve stimulations. A sparse adrenergic innervation of the detrusor muscle was found. It was supposed to originate from long adrenergic neurones. The trigonum area had a rich supply of adrenergic fibres, probably derived from short adrenergic neurones. A uniformly rich supply of acetylcholine‐esterase (AChE)‐positive nerves was found in the whole bladder. Postganglionic sympathetic denervation caused no detectable change of adrenergic or AChE‐positive nerves in the bladder, while parasympathetic decentralization or denervation produced a total disappearance of adrenergic fibres. The AChE‐positive nerves were appreciably reduced in number after parasympathetic decentralization and not detectable after postganglionic denervation. Neither adrenergic nor AChE‐positive ganglion cells could be demonstrated in the bladder wall. Electrical stimulation of the hypogastric nerves or the pelvic nerves distal to the pelvic ganglia elicited contraction of the detrusor muscle. The responses were not affected by hexamethonium, dihydroergotamine or propranolol but were slightly reduced by guanethidine, reduced to about 40% by atropine and potentiated by eserine. Stimulation of the pelvic nerve proximal to the pelvic ganglion was partially blocked by hexamethonium. It is concluded that the urinary bladder of the rat is supplied by postganglionic adrenergic fibres mainlyviathe pelvic nerves and only to a lesser extentviathe hypogastric nerves. Probably cholinergic fibres pass to the bladder mainlyviathe pelvic nerves but alsoviathe hypogastric nerves, having their cellbodies outside the bladder wall, partly proximal to the pelvic ganglia.