Endothelial Dysfunction and Hypertension in Rats Transduced With CYP4A2 Adenovirus

Abstract

Abstract-Vascular cytochrome P450 (CYP) 4A enzymes catalyze the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE), an eicosanoid which participates in the regulation of vascular tone by sensitizing the smooth muscle cells to constrictor and myogenic stimuli. This study was undertaken to investigate the consequences of CYP4A overexpression on blood pressure and endothelial function in rats treated with adenoviral vectors carrying the CYP4A2 construct. Intravenous injection of Adv-CYP4A2 increased blood pressure (from 114Ϯ1 to 133Ϯ1 mm Hg, PϽ0.001), and interlobar renal arteries from these rats displayed decreased relaxing responsiveness to acetylcholine, which was offset by treatment with an inhibitor of CYP4A. Relative to data in control rats, arteries from Adv-CYP4A2-transduced rats produced more 20-HETE (129Ϯ10 versus 97Ϯ7 pmol/mg protein, PϽ0.01) and less nitric oxide (NO; 4.2Ϯ1.6 versus 8.4Ϯ1 nmol nitriteϩnitrate/mg; PϽ0.05). They also displayed higher levels of oxidative stress as measured by increased generation of superoxide anion and increased expression of nitrotyrosine and gp91phox. Collectively, these findings demonstrate that augmentation in vascular 20-HETE promotes the development of hypertension and causes endothelial dysfunction, a condition characterized by decreased NO synthesis and/or bioavailability, imbalance in the relative contribution of endothelium-derived relaxing and contracting factors, and enhanced endothelial activation. T he endothelium plays a critical role in the short-and long-term regulation of the cardiovascular system. It serves as a protective barrier between tissues and circulating blood and functions to maintain vascular homeostasis by releasing bioactive factors in response to hemodynamic changes and blood borne signals. Such endothelial cell functions are impaired in many disease processes, including, diabetes, atherosclerosis, and hypertension.The expression of the cytochrome P450 (CYP) 4A and its catalytic activity as arachidonic acid -hydroxylase which produces 20-hydroxyeicosatetraenoic acid (20-HETE) has been linked to the regulation of vascular reactivity and tone and to the development of hypertension. This notion is substantiated by observations that 20-HETE promotes vasoconstriction, 1,2 that CYP4A expression and/or 20-HETE production is increased in vascular tissues of hypertensive animals, 3 and that interventions that decrease CYP4A expression and/or activity cause blood pressure to fall in animal models of hypertension. 4 -11 The vasoconstrictor action of 20-HETE is primarily attributed to inhibition of the large conductance Ca 2ϩ -activated K Their study demonstrated that 20-HETE attenuates acetylcholine-induced dilation in cremasteric arterioles of normotensive rats on a low salt diet and that inhibition of 20-HETE synthesis enhances arteriolar dilation to acetylcholine in hypertensive rats on a high salt diet. More recently, 20-HETE has been shown to functionally antagonize EDHF-mediated relaxation in small porcine coronary arteries. 20 In the pre...

Vascular Cytochrome P450 4A Expression and 20-Hydroxyeicosatetraenoic Acid Synthesis Contribute to Endothelial Dysfunction in Androgen-Induced Hypertension

“…At day 14, rats were anesthetized with phenobarbital (50 mg/kg of body weight); kidneys were perfused in situ, and renal interlobar arteries were microdissected as described. 13 …”

“…Western blot analysis of arterial segments was performed as described previously 13 using the following primary antibodies: CYP 4A1 polyclonal antibody (Daiichi Chemical Co); nitrotyrosine polyclonal antibody (Cayman Chemicals), gp91 phox and p47 phox polyclonal antibodies (Upstate Co), and endothelial NO synthase (eNOS) polyclonal antibody (Santa Cruz Biotechnology).…”

“…13 Superoxide anion levels were measured in isolated renal interlobar arteries by lucigenin chemiluminescence as described. 13,27 …”

“…11,12 Inhibition of vascular 20-HETE synthesis by intravenous administration of CYP4A1 or CYP4A2 antisense oligonucleotides decreases BP in normotensive and hypertensive rats, 6,7 whereas transduction with adenoviruses expressing the CYP4A2 protein increases vascular CYP4A expression and 20-HETE levels and augments BP. 13 A role for androgens in promoting elevation of BP is well recognized 14 and, according to recent studies, such a role may rely on increased synthesis of vascular 20-HETE. Hence, mice deficient in cyp4a14 (the mouse homologue of CYP4A2) displayed androgen-sensitive hypertension, which was reversed by castration.…”

Increase of 20-HETE Synthase after Brain Ischemia in Rats Revealed by PET Study with 11C-Labeled 20-HETE Synthase-Specific Inhibitor

“…It has been reported that 20-HETE acts as a potent vasoconstrictor of cerebral microvessels (Harder et al, 1994), and has an important role in the autoregulation of cerebral blood flow (Gebremedhin et al, 2000). 20-Hydroxyeicosatetraenoic acid has also been reported to induce the formation of oxygen radicals by interacting with nicotinamide adenine dinucleotide phosphate-oxidase and nitric oxide synthase (Wang et al, 2006;Cheng et al, 2008;Medhora et al, 2008). Previously, we reported that brain and plasma 20-HETE levels were significantly increased in the rat transient middle cerebral artery occlusion (tMCAO) model (Tanaka et al, 2007), and inhibition of 20-HETE synthesis by N-(3-chloro-4-morpholin-4-yl)phenyl-N'-hydroxyimido formamide (TS-011), a selective inhibitor of CYP4s, improved the autoregulatory dysfunction in the peri-infarct microcirculation and the neurologic outcomes in rat and monkey stroke models by reducing the infarct volume of the brain after ischemia (Miyata et al, 2005;Omura et al, 2006;Tanaka et al, 2007;Marumo et al, 2010).…”