Cytochrome P450 1B1 Contributes to Angiotensin II–Induced Hypertension and Associated Pathophysiology

Abstract

Abstract-Hypertension is the leading cause of cardiovascular diseases, and angiotensin II is one of the major components of the mechanisms that contribute to the development of hypertension. However, the precise mechanisms for the development of hypertension are unknown. Our recent study showing that angiotensin II-induced vascular smooth muscle cell growth depends on cytochrome P450 1B1 led us to investigate its contribution to hypertension caused by this peptide. Angiotensin II was infused via miniosmotic pump into rats (150 ng/kg per minute) or mice (1000 g/kg per day) for 13 days resulting in increased blood pressure, increased cardiac and vascular hypertrophy, increased vascular reactivity to vasoconstrictor agents, increased vascular reactive oxygen species production, and endothelial dysfunction in both species. The increase in blood pressure and associated pathophysiological changes were minimized by the cytochrome P450 1B1 inhibitor 2,3Ј,4,5Ј-tetramethoxystilbene in both species and was markedly reduced in Cyp1b1 Ϫ/Ϫ mice. These data suggest that cytochrome P450 1B1 contributes to angiotensin II-induced hypertension and associated pathophysiological changes. Moreover, 2,3Ј,4,5Ј-tetramethoxystilbene, which prevents both cytochrome P450 1B1-dependent and -independent components of angiotensin II-induced hypertension and inhibits associated pathophysiological changes could be clinically useful in the treatment of hypertension and associated cardiovascular and inflammatory diseases. (Hypertension. 2010;56:667-674.) Key Words: angiotensin II Ⅲ cytochrome P450 1B1 Ⅲ Cyp1b1 Ϫ/Ϫ mice Ⅲ blood pressure Ⅲ cardiac and vascular hypertrophy Ⅲ vascular reactivity Ⅲ endothelial function A ngiotensin II (Ang II) is a major component of the mechanisms regulating cardiovascular homeostasis by maintaining vascular tone and salt and water balance. 1 Ang II also activates cytosolic phospholipase A 2 and releases arachidonic acid (AA) from phospholipids. 2 AA is metabolized by cyclooxygenase into prostaglandins and thromboxane A 2 , by lipoxygenase into 5-, 12-, and 15-hydroxyeicosatetraenoic acids (HETEs), by cytochrome P450 (CYP) -hydroxylase into 20-HETE, and by epoxygenase into epoxyeicosatrienoic acids. 3 Prostaglandins E 2 and I 2 and epoxyeicosatrienoic acids contribute to antihypertensive mechanisms, 4,5 whereas prostaglandin precursor PGH 2 and 20-HETE contribute to prohypertensive mechanisms. 6 -8 The balance between these antihypertensive and prohypertensive eicosanoids, together with other vasoactive agents, determines blood pressure levels. Products of AA generated via lipoxygenase (12-HETE) or CYP 4A (20-HETE) also promote vascular smooth muscle cell (VSMC) migration, proliferation, or hypertrophy by activating extracellular signal-regulated kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (MAPK) 9 -13 and contribute to the vasoconstrictor action of Ang II. 14 Moreover, inhibitors of lipoxygenase and CYP 4A minimize Ang II-dependent hypertension. 6,15,16 Ang II and AA also stimulate production of reac...

Cytochrome P450 1B1 Is Critical for Neointimal Growth in Wire‐Injured Carotid Artery of Male Mice

“…Our finding that the CYP1B1 inhibitor 2,3′,4,5′‐tetramethoxystilbene minimizes hypertension, atherosclerosis, and abdominal aneurysms,5, 28, 29 while also attenuating neointimal growth in wire‐injured carotid artery of Cyp1b1 +/+ male mice, further supports our hypothesis that CYP1B1 is required for neointimal growth and suggests an important translational implication of this work. Thus, CYP1B1 could serve as a potential target for the development of novel agents for the treatment of restenosis after balloon angioplasty, or to coat drug‐eluting stents as antiproliferative agents in male mice.…”

“…We have previously reported that ROS generated via CYP1B1 contribute to the development of hypertension in different animal models, atherosclerosis, and abdominal aortic aneurysms 5, 28, 29. In the current study, wire injury of the carotid arteries increased superoxide production, as detected by 2‐hydroxyethidium fluorescence in Cyp1b1 +/+ mice, which was reduced in Cyp1b1 −/− mice.…”

“…We have previously reported that cytochrome P450 1B1 (CYP1B1), a heme‐thiolate monooxygenase expressed in cardiovascular tissues, contributes to the development of hypertension, and its associated pathogenesis 5. CYP1B1 also mediates angiotensin II (Ang II)–induced migration, proliferation, and growth of rat VSMCs, via generation of reactive oxygen species (ROS) 6.…”

Cytochrome P450 1B1 Contributes to the Development of Angiotensin II–Induced Aortic Aneurysm in Male Apoe−/− Mice

“…12 Briefly, tissue samples were homogenized (2 Â 3 minutes) in ice-cold 100 mmol/L potassium phosphate buffer (pH 7.4) using the TissueLyser II (Qiagen, Valencia, CA). Centrifugation was performed at 10,000 Â g for 20 minutes at 4 C. Protein contents in the samples were determined by the Bradford method, 500 mg of protein was added to a reaction mixture containing 20 mmol/L L-CEE substrate and 100 mmol/L potassium phosphate buffer (pH 7.4) and incubated at 37 C for 10 minutes, 100 mmol/L of NADPH (final concentration) was added, and the solution was further incubated at 37 C for 45 minutes.…”

“…7,8 The metabolism of fatty acids by cyclooxygenase (COX), lipoxygenase, and cytochrome P450 (CYP) enzymes results in the generation of ROS, 8,9 and ROS generated via the activation of NADPH oxidase appears to play a major role in the development of AAA. 10 Previously, we have shown that Ang IIeinduced vascular smooth muscle cell (VSMC) migration, proliferation and hypertrophy, 11 and hypertension 12 depend on CYP1B1, 11,12 a heme-thiolate monooxygenase that is expressed in extrahepatic tissues, including those in the cardiovascular system, 13 and is involved in activating NADPH oxidase and generating ROS. 11e13 These observations led us to the hypothesis that Ang IIeinduced AAA and associated pathogenesis are mediated by CYP1B1-generated ROS.…”