Nervous control of urinary bladder in cats. 3. Effects of autonomic blocking agents in the intact animal.

Abstract

AbstractEdvardsen, P. Nervous control of urinary bladder in cats. III. Effects of autonomic blocking agents in the intact animal. Acta physiol. scand. 1968. 72. 183–193.Bladder motility in anesthetized or decerehrated cats was recorded under isometric conditions before and after the administration of graded doses of various agents with peripheral or ganglionic blocking effects on the autonomic nervous system. Direct or indirect cystometry was employed when the effects on the collecting or on the expulsion phase, respectively, were studied. Atropine, which blocks at cholinergic receptor sites, made the micturition contraction inefficient as the ability of the bladder to sustain the initial contraction was abolished. Hexamethonium, which blocks ganglionic transmission, impaired the spontaneous micturition contraction as well: by also preventing, the initial pressure rise from occurring. The drug blocked the sympathetic ganglia at doses smaller than those which blocked the parasympathetic ones. The effects of propranolol and dibenzyline, which block adrenergic inhibitory and excitatory receptors respectively, suggest that both these receptors are present in the bladder. The former drug increased bladder tone, the latter had an atropine‐like effect on the micturition contraction and an excitatory influence on the micturition reflex. Finally, guanethidine, which blocks the adrenergic neuro‐muscular junction, had an excitatory effect on the bladder and a facilitatory effect on the micturition reflex in addition to its presynaptic blocking effect. These results support previous hypotheses of a sympathetic inhibition and absence of parasympathetic activity during the collecting phase, and of bladder pressure as the determinant of the micturition threshold.