Decreased Levels of Cytochrome P450 2E1–Derived Eicosanoids Sensitize Renal Arteries to Constrictor Agonists in Spontaneously Hypertensive Rats

Abstract

We compared renal interlobar arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) in terms of cytochrome P450 (CYP) 4A and CYP2E1 protein expression; levels of 20-HETE, 19-HETE, and 18-HETE; and responsiveness to phenylephrine in the absence and presence of N- methylsulfonyl-12,12-dibromododec-11-enamide (DDMS; 30 μmol/L), a CYP4A inhibitor. Relative to data in WKY, arteries of SHR exhibited diminished ( P <0.05) CYP2E1 and levels of 19-HETE (66.7±6.0 versus 44.9±2.8 pmol/mg) and 18-HETE (13.8±1.6 versus 7.9±0.5 pmol/mg), whereas CYP4A and 20-HETE levels (99.3±9.1 versus 98.9±12.8 pmol/mg) were unchanged. Phenylephrine contracted vascular rings of SHR and WKY; the R max was similar in both strains, but SHR vessels were more sensitive as denoted by the lower ( P <0.05) EC 50 (0.28±0.07 versus 0.71±0.12 μmol/L). DDMS decreased 20-HETE and, to a lesser extent, 19-HETE, while increasing ( P <0.05) the EC 50 for phenylephrine by 475% and 54% in vessels of SHR and WKY, respectively. The desensitizing effect of DDMS was reversed by 20-HETE. Notably, the minimal concentration of 20-HETE that decreased the EC 50 for phenylephrine in DDMS-treated vessels was smaller in SHR (0.1 μmol/L) than WKY (10 μmol/L), and the sensitizing effect of 20-HETE was blunted ( P <0.05) by the (R) stereoisomers of 19-HETE and 18-HETE. We conclude that the increased sensitivity to phenylephrine in arteries of SHR is attributable to a vasoregulatory imbalance produced by a deficit in vascular CYP2E1-derived products, most likely 19(R)-HETE and 18(R)-HETE, which condition amplification of the sensitizing action of 20-HETE.