Reflex effects of slow bladder filling on the blood pressure in cats.

Abstract

The effect of slow bladder distension on mean arterial blood pressure has been studied in the cat anawsthetized with chloralose. In fifteen cats out of eighteen, slow bladder filling was associated with a steady rise in blood pressure of not more than 30 mm.Hg.; this rise was slowly adapting or compensated, and was unaffected by baroreceptor denervation. In eleven out of fourteen cats, spontaneous isometric bladder contractions were associated with a rise in blood pressure of more than 20 mm. Hg which was rapidly compensated, and was accentuated after baroreceptor denervation. In fifteen cats out of eighteen, bladder emptying was associated with a fall in blood pressure, the blood pressure returning to the basal level after an initial overshoot. No changes in blood pressure were observed in response to direct pressure on the bladder or to bladder ischæmia. Three cats out of a total of twenty‐nine showed depressor or biphasic blood pressure responses to slow bladder filling and to spontaneous isometric bladder contractions. Possible afferent receptors for these bladder viscero‐vascular reflexes are discussed; and consideration is given to the rôle of the cardiovascular stabilizing reflexes in partially compensating the spinal viscerovascular reflexes in the intact animal.