Functional and morphological properties of pericytes in suburothelial venules of the mouse bladder.

ABSTRACT: BACKGROUND AND PURPOSE: In suburothelial venules of rat bladder, pericytes (perivascular cells) develop spontaneous Ca(2+) transients, which may drive the smooth muscle wall to generate spontaneous venular constrictions. We aimed to further explore the morphological and functional characteristics of pericytes in the mouse bladder. EXPERIMENTAL APPROACH: The morphological features of pericytes were investigated by electron microscopy and fluorescence immunohistochemistry. Changes in diameters of suburothelial venules were measured using video microscopy, while intracellular Ca(2+) dynamics were visualized using Fluo-4 fluorescence Ca(2+) imaging. KEY RESULTS: A network of ?-smooth muscle actin immunoreactive pericytes surrounded venules in the mouse bladder suburothelium. Scanning electron microscopy revealed that this network of stellate-shaped pericytes covered the venules, while transmission electron microscopy demonstrated that the venular wall consisted of endothelium and adjacent pericytes, lacking an intermediate smooth muscle layer. Pericytes exhibited spontaneous Ca(2+) transients, which were accompanied by phasic venular constrictions. Nicardipine (1 ?M) disrupted the synchrony of spontaneous Ca(2+) transients in pericytes and reduced their associated constrictions. Residual asynchronous Ca(2+) transients were suppressed by cyclopiazonic acid (10 ?M), 2-aminoethoxydiphenyl borate (10 ?M), U-73122 (1 ?M), oligomycin (1 ?M) and SKF96365 (10 ?M), but unaffected by ryanodine (100 ?M) or YM-244769 (1 ?M), suggesting that pericyte Ca(2+) transients rely on Ca(2+) release from the endoplasmic reticulum via the InsP(3) receptor and also require Ca(2+) influx through store-operated Ca(2+) channels. CONCLUSIONS AND IMPLICATIONS: The pericytes in mouse bladder can generate spontaneous Ca(2+) transients and contractions, and thus have a fundamental role in promoting spontaneous constrictions of suburothelial venules.

SUBMITTER: Hashitani H 

PROVIDER: S-EPMC3525874 | biostudies-other | 2012 Dec

REPOSITORIES: biostudies-other