Abstract

The mechanisms that mediate the cardiovascular protective effects of omega 3 (n-3) polyunsaturated fatty acids (PUFAs) have not been fully elucidated. Cytochrome P4501A1 (CYP1A1) efficiently metabolizes n-3 PUFAs to potent vasodilators. Thus, we hypothesized that dietary n-3 PUFAs increase nitric oxide (NO)-dependent blood pressure regulation and vasodilation in a CYP1A1-dependent manner. CYP1A1 wild type (WT) and knockout (KO) mice were fed an n-3 or n-6 PUFA-enriched diet for eight weeks and were analyzed for tissue fatty acids and metabolites, NO-dependent blood pressure regulation, NO-dependent vasodilation of acetylcholine (ACh) in mesenteric resistance arterioles, and endothelial NO synthase (eNOS) and phospho-Ser1177-eNOS expression in aorta. All mice fed the n-3 PUFA diet showed significantly higher levels of n-3 PUFAs and their metabolites, and significantly lower levels of n-6 PUFAs and their metabolites. In addition, KO mice on the n-3 PUFA diet accumulated significantly higher levels of n-3 PUFAs in aorta and kidney without a parallel increase in the levels of their metabolites. Moreover, KO mice exhibited significantly less NO-dependent regulation of blood pressure on the n-3 PUFA diet and significantly less NO-dependent, ACh-mediated vasodilation in mesenteric arterioles on both diets. Finally, the n-3 PUFA diet significantly increased aortic phospho-Ser1177-eNOS/eNOS ratio in the WT compared to KO mice. These data demonstrate that CYP1A1 contributes to eNOS activation, NO bioavailability, and NO-dependent blood pressure regulation mediated by dietary n-3 PUFAs.