title: Contribution of cytochrome P450 metabolites to bradykinin-induced vasodilation in endothelial NO synthase deficient mouse hearts.
abstract: We have characterized the contribution of endothelial nitric oxide synthase (eNOS), cyclo-oxygenase (COX) and cytochrome P450 (CYP450) to the bradykinin (BK)- induced vasodilation in isolated hearts from wildtype (WT) and eNOS deficient mice (eNOS-/-). The endothelium-dependent vasodilation by bradykinin (BK, 1 microM) was significantly lower in eNOS-/- hearts than that in WT hearts (+247% and +325% of basal flow, respectively), while there was no difference in the endothelium-independent vasodilation by adenosine. In WT hearts, the BK-induced vasodilation was markedly attenuated following inhibition of NOS with ETU (10 microM) but not after COX inhibition with diclofenac (3 microM) (P<0.01). In line with this finding, Bk did not increase the cardiac prostacyclin release as measured by ELISA for 6-keto-PGF1alpha in the coronary venous effluent. In eNOS-/- hearts, the flow response to BK was insensitive to both NOS and COX inhibition. The NOS/COX-independent vasodilatory factor which remained under L-NMMA+DF application was almost completely eliminated by either clotrimazole (3 microM), miconazole (0.5 microM) or 17-ODYA (1 microM), suggesting that it was a metabolite of CPY450 enzymes. Sulfaphenazole (10 microM), a CYP450 2C inhibitor, exerted only a minimal inhibitory effect. In eNOS-/- hearts the effect of CYP450 inhibitors on the BK response was significantly more pronounced than in WT hearts, indicating an enhanced contribution of CYP450 enzymes. These findings suggest that in isolated mouse hearts the BK-induced vasodilation is mediated by NO and CYP450 metabolites but not by prostaglandins. The CYP450 dependent vasodilator was was functionally up-regulated in eNOS-/- hearts and thus likely to compensate for the loss of eNOS in the coronary circulation.
authors.affiliation: Institut für Herz- und Kreislaufphysiologie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany.
authors.forename: Zhaoping
authors.initials: Z
authors.lastname: Ding
authors.forename: Axel
authors.initials: A
authors.lastname: Gödecke
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schrader
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology / Q000502:physiology*; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism* / Q000502:physiology; D004699:Endocardium / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000172:deficiency* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D011453:Prostaglandins / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000235:genetics / Q000502:physiology*
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D011453:Prostaglandins; D009569:Nitric Oxide; D003577:Cytochrome P-450 Enzyme System; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D001920:Bradykinin