Resveratrol Stimulates the Na+–Ca2+ Exchanger on the Plasma Membrane to Reduce Cytosolic Ca2+ in Rat Aortic Smooth Muscle Cells

Resveratrol is well known to exhibit vascular relaxant and antihypertensive effects. In this study, we determined the effects of resveratrol on the modulation of cytosolic [Ca] level and adenosine 5'-triphosphate-induced Ca release from the sarcoplasmic reticulum (SR) in rat aortic smooth muscle cells (ASMCs) and explored its underlying mechanisms. In this article, cytosolic [Ca] and SR [Ca] in ASMCs were determined by Fluo-4/acetoxymethyl and Mag-Fluo-4/acetoxymethyl respectively. Resveratrol (20, 50, and 100 µM) caused a rapid and substantial reduction in cytosolic [Ca] in ASMCs bathed in normal Hank's Balanced Salt Solution or Ca-free Hank's Balanced Salt Solution. Pretreatment with resveratrol reduced adenosine 5'-triphosphate-induced SR Ca release and SR Ca content. In the cells bathed in Na-free physiological saline, which favors the reverse mode of the Na-Ca exchanger (NCX), resveratrol induced an increase in cytosolic [Ca] and SR [Ca]. However, its effect on cytosolic [Ca] was inhibited by the selective NCX inhibitor, SEA0400. Our findings suggest that resveratrol reduces cytosolic [Ca] and SR [Ca] in ASMCs in normal physiological saline, which might be, at least in part, mediated by the NCX.