The Adrenergic Innervation and Adrenergic Receptor Activity of the Feline Urinary Bladder and Urethra in the Normal State and After Hypogastric and/or Parasympathetic Denervation

Abstract

After long-term parasymphatetic denervation, detrusor muscle hypertrophy was found regardless of whether the hypogastric nerves had been sectioned simultaneously or not. After hypogastric denervation only, there was no difference in gross appearance from normal bladders.

Adrenergic innervation was studied by means of a histochemical fluorescence technique. After hypogastric denervation, there was usually a slight increase in the detrusor innervation and a clear decrease in the trigone and urethral adrenergic innervation. After parasympathetic denervation, the detrusor showed an increase in adrenergic innervation, while the innervation of the trigone and the urethra was unchanged. After simultaneous parasympathetic and hypogastric denervation, the adrenergic innervation of the detrusor was similar to that of the bladders subjected to parasympathetic denervation only. The adrenergic innervation of the trigone and urethra was similar to that found after hypogastric denervation only.

Adrenergic receptor functions were studied by a method in which changes in the isometric tension of muscle strips were recorded following different pharmacological treatments. In the normal state, noradrenalin and phenylephrine caused contraction and isoprenaline relaxation of the trigone-urethra. In the detrusor, noradrenalin caused relaxation of strips contracted by carbacholine. Relaxed detrusor muscle strips were usually not contracted by noradrenalin. In 2 out of 8 normal cats, however, a contraction was observed after very large doses of noradrenalin. After hypogastric denervation, the adrenoreceptor functions were consistent with those of the normal state. After parasympathetic denervation, the trigone-urethral receptor functions were unchanged compared with the normal receptor functions. In the detrusor, isoprenaline caused relaxation and noradrenalin and phenylephrine contraction. After simultaneous parasympathetic and hypogastric denervation, the results were consistent with those obtained after parasympathetic denervation only.

Thus, the present study showed an increased adrenergic detrusor innervation and α-receptor activity after parasympathetic denervation regardless of whether the hypogastric nerves had been sectioned simultaneously or not. Although α-receptors might exist in the normal detrusor, β-receptors dominate strongly. After parasympathetic denervation, there seems to be a change in the relation between α- and β-receptors in favour of α-receptors.