Inhibition of 20-HETE Production Contributes to the Vascular Responses to Nitric Oxide

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Abstract
Nitric oxide (NO) inhibits a variety of heme-containing enzymes, including NO synthase and cytochrome P4501A1 and 2B1. The present study examined whether NO inhibits the production of 20-hydroxyeicosatetraenoic acid (20-HETE) by cytochrome P4504A enzymes and whether blockade of the production of this substance contributes to the vascular effects of NO. Sodium nitroprusside (SNP; 10−5, 10−4, and 10−3 mol/L) reduced the production of 20-HETE by renal microsomes incubated with arachidonic acid to 71±5%, 29±4%, and 4±2% of control, respectively (n=5). Similar results were obtained with the use of 1-propanamine, 3-(2-hydroxy-2-nitroso-1-propylhydrazino) (n=3). To determine whether inhibition of 20-HETE contributes to the vasodilatory effects of NO, the effects of dibromo-dodecenyl-methylsulfimide (DDMS), a selective inhibitor of the formation of 20-HETE, on the response to SNP (10−7 to 10−3 mol/L) were examined in rat renal arterioles preconstricted with phenylephrine (n=5). SNP increased vascular diameter in ...