Abstract 1436: CYP2J2 Endothelial Overexpression Increases Nitric Oxide and Cyclooxygenase Independent Renal Dilation and Attenuates Endothelin-1 Vasoconstriction

Abstract

Human CYP2J2 is expressed in endothelial cells and active in the biosynthesis of epoxyeico-satrienoic acids (EETs). However, the functional role of CYP2J2 and its products in the renal vasculature remain poorly characterized. To address this, we developed transgenic (Tr) mice with constitutive, endothelial cell-specific expression of human CYP2J2 ( Tie2 promoter and full enhancer) and enhanced EET biosynthesis. Experiments were conducted in the juxtamedullary nephron preparation to determine renal microvascular responses to acetylcholine (ACh) and endothelin-1 in Tie2 -CYP2J2 Tr mice and wild type (Wt) littermate controls. Administration of phenylephrine to kidney perfusate decreased the diameter of afferent arterioles from 20.1±0.5 to 13.9±0.6 μm (n=21) in Wt mice and 19.4±0.6 to 13.5±0.6 μm (n=23) in Tie2 -CYP2J2 Tr mice. Following phenylephrine, the afferent arteriole diameter response to ACh (0.01nM-10μM) was determined. There was a leftward shift in the logEC50 in Tie2 -CYP2J2 Tr mice (−6.5±0.2, n=13) compared to Wt mice (−6.1±0.2, n=11). However, the maximal afferent arteriolar relaxation to ACh was decreased in Tie2 -CYP2J2 Tr mice (59±6%) compared to Wt mice (70±7%, p=0.12). Endothelial expression of CYP2J2 increased the maximal renal vascular response to ACh in the presence of nitric oxide synthase (100μM L-NAME) and cyclooxygenase (10μM indomethacin) inhibition. Afferent arterioles relaxed by 27±4% (n=12) in Wt mice and 44±6% (n=10, p=0.018) in Tie2 -CYP2J2 Tr mice (10μM ACh). The afferent arteriolar dose response curve to endothelin-1 (0.001–10nM) was significantly attenuated in Tie2 -CYP2J2 Tr compared to Wt mice. Afferent arteriolar diameter decreased by 24±4% (n=6) in Wt mice and 13±2% (n=5, p=0.023) in Tie2 -CYP2J2 Tr mice (3nM endothelin-1). These results demonstrate that the nitric oxide- and cyclooxygenase-independent afferent arteriolar dilation to ACh is enhanced by endothelial overexpression of CYP2J2, and endothelin-1 mediated constriction is attenuated. In conclusion, endothelial overexpression of CYP2J2 can oppose renal vascular constrictor responses and enhance dilator responses in mice, implicating the important role of CYP2J2-derived eicosanoids in the regulation of vascular tone.