Vascular Smooth Muscle TRPV4 (Transient Receptor Potential Vanilloid Family Member 4) Channels Regulate Vasoconstriction and Blood Pressure in Obesity
Yifei Zhu, Yuan Chu, Sheng Wang, Junjian Tang, Hu Li, Lei Feng, Fan Yu, Xin Ma
Abstract
Background: Vascular endothelium and smooth muscle work together to keep the balance of vasomotor tone and jointly maintain vascular homeostasis. Ca 2+ -permeable ion channel TRPV4 (transient receptor potential vanilloid family member 4) in endothelial cells regulates endothelium-dependent vasodilation and contraction in various states. However, how vascular smooth muscle cell TRPV4 (TRPV4 SMC ) contributes to vascular function and blood pressure regulation in physiological and pathologically obese condition has not been fully studied. Methods: We generated smooth muscle TRPV4-deficient mice and developed diet-induced obese mice model and analyzed the role of TRPV4 SMC in intracellular Ca 2+ ([Ca 2+ ] i ) regulation and vasoconstriction. Vasomotor changes of mouse mesenteric artery were measured by wire, and pressure myography. [Ca 2+ ] i were measured by fluo-4 staining. Blood pressure was recorded by telemetric device. Results: Vascular TRPV4 SMC played different roles in regulating vasomotor tone than endothelial TRPV4 due to their different features of [Ca 2+ ] i regulation. Loss of TRPV4 SMC attenuated U46619- and phenylephrine-induced contraction, suggesting its involvement in regulating vascular contractility. Mesenteric arteries from obese mice showed SMC hyperplasia, suggesting an increased level of TRPV4 SMC . Loss of TRPV4 SMC did not influence the development of obesity but protected mice from obesity-induced vasoconstriction and hypertension. In arteries deficient in SMC TRPV4, SMCs F-actin polymerization and RhoA dephosphorylation were attenuated under contractile stimuli. Moreover, SMC-dependent vasoconstriction was inhibited in human resistance arteries with TRPV4 inhibitor application. Conclusions: Our data identify TRPV4 SMC as a regulator of vascular contraction in both physiological states and pathologically obese mice. TRPV4 SMC contributes to the ontogeny of vasoconstriction and hypertension induced by TRPV4 SMC over-expression in obese mice mesenteric artery.