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

The role of the Ca-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 activation of cytosolic phospholipase A2 (cPLA) in the aortic endothelial cells of obese mice. Acetylcholine-induced endothelium-dependent relaxation and contraction in the aorta were measured using wire myography. PLA activity was measured by the fluorogenic PLA substrate Bis-BODIPY™ FL C-PC. The intracellular Ca 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 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 (PGF) and E (PGE) 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 and enhanced COX-2-PGF/PGE levels in DIO mice.