Spatial separation of endothelial small- and intermediate-conductance calcium-activated potassium channels (K(Ca)) and connexins: possible relationship to vasodilator function?

摘要: Activation of endothelial cell small- (S) and intermediate- (I) conductance calcium-activated potassium channels (KCa) current or molecular transfer via myoendothelial gap junctions underlies endothelium-derived hyperpolarization leading to vasodilation. The mechanism underlying the KCa component vasodilator activity characteristics are targets for selective control vascular function. In rat mesenteric artery, where connexin (Cx) 40 critical transmission smooth muscle, SKCa IKCa provide different facets response, being repolarization phases, respectively. present study addressed question whether this functional separation responses may be related spatial localization associated channels? distribution Cx subtype(s) were examined in artery using conventional confocal high-resolution ultrastructural immunohistochemistry. At internal elastic lamina–smooth muscle interface at lamina holes (as potential junction sites), strong punctate IKCa, Cx37 Cx40 expression was present. SKCa, Cx37, Cx43 localized adjacent junctions. High-resolution immunohistochemistry demonstrated Cx37-conjugated gold junction-associated projections. Clear co-localization Cxs suggests a causal relationship between their previously described differential activation IKCa. Such precise localizations represent target function tone.