CYP2C29 Produces Superoxide in Response to Shear Stress

OBJECTIVE: Activation of CYP2C29 releases superoxide during shear stress-induced dilation (SSID). METHODS: Mesenteric arteries isolated from female eNOS-KO and WT mice were cannulated and pressurized. Vasodilation and superoxide production in response to shear stress were assessed. RESULTS: Shear stress-induced dilation was significantly attenuated in vessels of eNOS-KO compared with WT mice, which was normalized by tempol and PEG-Catalase, in a PPOH (inhibitor of CYP2C29)-sensitive manner, but remained unaffected by VAS2870 and allopurinol, inhibitors of NADPH oxidase and xanthine oxidase, respectively. NaNO(2)-induced dilation was comparable in both strains of mice. Confocal microscopy shows that SS-stimulated superoxide was increased particularly in the endothelium of eNOS-KO mice. HPLC analysis of 2-EOH indicated an increase in SS-stimulated superoxide in vessels of eNOS-KO mice, a response that was sensitive to PPOH. Inhibition of soluble epoxide hydrolase significantly enhanced SSID without affecting SS-stimulated superoxide production. CYP2C29 and catalase were upregulated, and exogenous H(2)O(2) caused vasoconstriction in vessels of eNOS-KO mice. CONCLUSIONS: CYP2C29 synthesizes EETs to mediate SSID, and simultaneously releases superoxide and sequential H(2)O(2), which in turn impair SSID.