Sex differences and role of nitric oxide in blood flow of canine urinary bladder

Continuous measurements were made of bladder blood flow by laser Doppler fl owmetry in anesthetized dogs during bladder filling and emptying. In both m ucosa and muscle, perfusion was inversely proportional to intravesical pres sure. There was significantly greater perfusion in the bladder mucosa of ma les than females at baseline and up to 10 cm water filling pressure but not in the muscle. Intra-arterial infusion of the nitric oxide synthase inhibi tor N-G-nitro-L-arginine produced a significant decrease in resting bladder perfusion in the mucosa only, with no differences seen in the response to intravesical pressure. Intra-arterial infusion of L-arginine produced a sig nificant increase in the level of perfusion in the mucosa seen immediately after the bladder was drained. No changes were observed in muscle perfusion after L-arginine. These results suggest that the perfusion of the bladder mucosa differs by gender and is regulated differently than the bladder musc le, possibly related to the different function of the two layers.