TRPC5 is essential in endothelium-dependent contraction of aorta from diet-induced obese mice

The role of the Ca 2+ -permeable ion channel TRPC5 in regulating vasocontraction in obesity is poorly understood. Here, we investigated whether TRPC5 contributes to vascular dysfunction in obesity by promoting endothelium-dependent contraction via activation of cytosolic phospholipase A2 (cPLA 2 ) in the aortic endothelial cells of obese mice. Acetylcholine-induced endothelium-dependent relaxation and contraction in the aorta were measured using wire myography. PLA 2 activity was measured by the fluorogenic PLA 2 substrate Bis-BODIPY™ FL C 11 -PC. The intracellular Ca 2+ level in response to acetylcholine was measured by Fluo-4 fluorescence. Endothelium-derived contracting factors were assessed by enzyme immunoassay. Diet-induced obesity (DIO) attenuated endothelium-dependent vasodilation, enhanced endothelium-dependent contraction (EDC), and increased the expression of TRPC5 in the mouse aorta. Activation of TRPC5 promoted EDC in the wild-type mouse aorta, whereas pharmacological inhibition and genetic knockout of TRPC5 decreased EDC in the DIO mouse aorta. Moreover, cPLA 2 phosphorylation and activity were higher in aortic endothelial cells from DIO mice, and this was attenuated by inhibition and knockout of TRPC5. Cyclooxygenase 2 (COX-2) expression was increased in DIO mouse endothelium and was decreased by a TRPC5 inhibitor and knockout of TRPC5. Release of prostaglandins F 2α (PGF 2α ) and E 2 (PGE 2 ) was involved in TRPC5-regulated EDC in DIO mice. This study demonstrated that TRPC5 contributes to endothelial and vascular dysfunction and is involved in EDC through activation of cPLA 2 and enhanced COX-2-PGF 2α /PGE 2 levels in DIO mice.