Functional Properties of Suburothelial Microvessels in the Rat Bladder

Abstract

Spontaneous vasoconstriction of suburothelial venules appears to result upon Ca(2+) release from the sarcoplasmic reticulum upon activation of inositol 1,4,5-trisphosphate receptors. This Ca(2+) opens Ca(2+) activated Cl(-) channels to trigger action potentials and Ca(2+) influx through L-type Ca(2+) channels. Adjacent perivascular interstitial cells may also have a role in generating this spontaneous venular vasoconstriction. In contrast, sympathetic nerve released noradrenaline acts on α(1A)-adrenoceptors to constrict suburothelial arterioles.

Calcium Signalling in Pericytes

“…Confocal Ca 2+ imaging has brought many advantages to the study of Ca 2+ signalling in situ. Confocal images of vessels permit the visualization of individual vascular smooth muscle cells, pericytes and endothelial cells, and so quantification of changes of Ca 2+ signals in these cells can be made and then correlated with mechanical or electrical events [12,13,14,15,16,17,18]. In this review, we attempt to summarize our results and those of other authors over the last 2 decades in the field of Ca 2+ signalling in pericytes.…”

Urothelial Signaling

“…Noradrenergic nerves in the LP, considered to have vasomotor function, were demonstrated by Jen, Gosling and Dixon (147), and functional support for noradrenergic innervation of suburothelial microvessels has been presented (127).…”

Inhibition of vascular smooth muscle inward-rectifier K+channels restores myogenic tone in mouse urinary bladder arterioles

“…2). Electrical field stimulation-induced constriction of bladder submucosal arterioles is blocked by the ␣ 1 antagonist prazosin (18), indicating sympathetic innervation of these vessels. However, other nerves, including cholinergic, nitrergic, and primary affer- ent nerves, may also innervate these vessels, setting the stage for complex, heterogeneous neural regulation of bladder blood flow (28,39).…”

“…These observations suggest the importance of minimizing the duration and magnitude of ischemia in maintaining proper bladder function, but provide few insights into the regulation of bladder blood flow per se. Ex vivo experiments have shown that the ␣1 antagonist prazosin blocks electrical field stimulation-induced constriction of submucosal arterioles, suggesting a role for sympathetic innervation of these vessels in regulating bladder arteriolar diameter, and by extension, bladder blood flow (18). Beyond this, very little is known about the properties of the bladder vasculature, and how these vessels regulate bladder blood flow before, during, and after micturition.…”