Effect of KW-7158, a putative afferent nerve inhibitor, on bladder and vesico-vascular reflexes in rats.

The effects of KW-7158, a putative afferent nerve inhibitor, on reflex bladder activity and vesico-vascular reflexes were evaluated in urethane anesthetized SD rats with normal and xylene-irritated bladders. The bladder was filled with saline until the appearance of large amplitude spontaneous bladder contractions (LA-BC). Vesico-vascular reflexes were measured as increases in systolic arterial blood pressure during LA-BC or when the bladder was distended by a range of pressures. In normal rats, KW-7158 (10 and 100 microg/kg, i.v.) did not alter the amplitude or volume threshold for inducing LA-BC but increased the intercontraction interval. After xylene-irritation, which decreased volume threshold and intercontraction interval and induced small amplitude bladder contractions, KW-7158 increased volume threshold (65%) and intercontraction interval (150%) and decreased the number of small amplitude bladder contractions. Vesico-vascular reflexes induced during LA-BC or by bladder distension were suppressed (19.4-100%) by KW-7158. The effect of KW-7158 to depress vesico-vascular reflexes as well as xylene-induced bladder hyperactivity without altering the amplitude of contractions is consistent with the view that the drug affects reflex bladder activity at least in part by depressing afferent pathways.