Differential role of STIM1 in calcium handling in coronary and intrarenal arterial smooth muscles.

Calcium (Ca) dysregulation contributes to various vascular diseases, but the role and underlying mechanism of stromal interaction molecule-1 (STIM1) in Ca signaling and vasocontraction remain elusive. By using smooth muscle-specific STIM1 knockout (sm-STIM1 KO) mice and a multi myograph system, we investigated the differential role of STIM1 in Ca handling between coronary and intrarenal arterial smooth muscles. After STIM1 deletion, contractile responses to 5-HT were obviously reduced in coronary and intrarenal arteries in the sm-STIM1 KO mice, but not altered in U46619. Phenylephrine barely induced the contraction of coronary arteries, we only detected an effect on the contraction of intrarenal arteries, which was also reduced in the sm-STIM1 KO mice. Then, L-type Ca channel (Cav1.2)- mediated vasocontractions were significantly enhanced in coronary and intrarenal arteries in sm-STIM1 KO mice, similar to treatment with the Cav1.2 agonist Bay K8644 in coronary arteries. However, non-Cav1.2-mediated vasocontractions were remarkably reduced. IP receptor- and ryanodine receptor-mediated vasocontractions were both obviously decreased in coronary and intrarenal arteries in sm-STIM1 KO mice. Moreover, STIM1-mediated store operated Ca entry (SOCE) only participated in the contraction of intrarenal arteries. In conclusion, we demonstrate that STIM1 participates in Cav1.2, sarcoplasmic reticulum (SR) Ca release and store-operated Ca (SOC) channels-mediated vasocontraction, which exhibits obvious organ-specificity between coronary and intrarenal arteries.