TRIC(trimeric intracellular cation)-Aチャネルは血管平滑筋において血圧調節に寄与する

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TRIC (trimeric intracellular cation) channel subtypes, namely TRIC-A and TRIC-B, are intracellular monovalent cation channels postulated to mediate counter-ion movements facilitating physiological Ca2+ release from intracellular stores. Tric-a-knockout mice developed hypertension during the daytime due to enhanced myogenic tone in resistance arteries. There are two Ca2+ release mechanisms in vascular smooth muscle cells (VSMCs); incidental opening of ryanodine receptors (RyRs) generates local Ca2+ sparks to induce hyperpolarization, while agonist-induced activation of inositol trisphosphate receptors (IP3Rs) evokes global Ca2+ transients causing contraction. Tric-a gene ablation inhibited RyR-mediated hyperpolarization signaling to stimulate voltage-dependent Ca2+ influx, and adversely enhanced IP3R-mediated Ca2+ transients by overloading Ca2+ stores in VSMCs. Therefore, TRIC-A channels contribute to maintaining blood pressure in vascular smooth muscles.