Mechanisms underlying heterogeneous Ca2+ sparklet activity in arterial smooth muscle.

摘要: In arterial smooth muscle, single or small clusters of Ca(2+) channels operate in a high probability mode, creating sites nearly continual influx (called "persistent sparklet" sites). Persistent sparklet activity varies regionally within any given cell. At present, the molecular identity underlying sparklets and mechanisms that give rise to their spatial heterogeneity remain unclear. Here, we used total internal reflection fluorescence (TIRF) microscopy directly investigate these issues. We found tsA-201 cells expressing L-type Cavalpha1.2 recapitulated general features cerebral myocytes, including amplitude quantal event, voltage dependencies, gating modalities, pharmacology. Furthermore, PKCalpha was required for basal persistent myocytes cells. inhibition protein phosphatase 2A (PP2A) 2B (PP2B; calcineurin) increased by evoking new increasing previously active sites. The actions PP2A PP2B on PKC activity, indicating phosphatases opposed PKC-mediated phosphorylation. Together, data unequivocally demonstrate is fundamental property when associated with PKC. Our findings support novel model which modality vary cell depending relative activities nearby PKCalpha, PP2A, PP2B.