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

The role of the Ca²⁺-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 (cPLA₂) in the aortic endothelial cells of obese mice. Acetylcholine-induced endothelium-dependent relaxation and contraction in the aorta were measured using wire myography. PLA₂ activity was measured by the fluorogenic PLA₂ substrate Bis-BODIPY™ FL C₁₁-PC. The intracellular Ca²⁺ 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, cPLA₂ 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 E₂ (PGE₂) 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 cPLA₂ and enhanced COX-2-PGF_2α/PGE₂ levels in DIO mice.