The adrenergic innervation of the urinary bladder in the cat and man in the normal state and after parasympathetic denervation.

The adrenergic innervation of the feline and human urinary bladder was studied with the histochemical fluorescence method of Hillarp and Falck. In the normal bladder of both species the trigone area was densely innervated by thick and strongly green-fluorescent adrenergic terminals while the detrusor muscle contained a sparse innervation of very thin and weakly fluorescent nerve terminals. After parasympathetic denervation (lower motor neuron lesion in patients) the adrenergic innervation of the detrusor muscle was altered. In the cat, the first signs of altered adrenergic innervation were observed 6 weeks after parasympathetic denervation, when thick, strongly fluorescent adrenergic fibres appeared between and in the smooth muscle bundles. These fibres had the characteristics of growth cones and indicated an outgrowth of new adrenergic fibres into the detrusor muscle. Later on, the muscle bundles were densely innervated by thick and strongly fluorescent terminals, reminiscent of trigone terminals. In the patients with lower motor neuron lesions, thick, strongly fluorescent adrenergic terminals were seen in the detrusor. In both cat and man the appearance of this "new" type of adrenergic nerve terminal in the detrusor muscle coincided with the presence of alpha-adrenoceptor function (rather than the normal beta-adrenoceptor activity of the feline and human detrusor).