Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A decrease in plasma Ca2+ and increases in plasma immunoreactive parathyroid hormone (PTH) have been reported in spontaneously hypertensive (SH) rats as compared with normotensive Wistar-Kyoto (WKy) rats. These changes should lead to a higher plasma 1,25(OH)2D (1,25-dihydroxycholecalciferol/1,25-dihydroxyergocalciferol) concentration in SH rat if the kidney responds appropriately. Plasma 1,25(OH)2D, however, has been reported to be normal in SH rats, suggesting possible impairments of vitamin D metabolism in this animal model of hypertension. To test this possibility, we studied the effect of PTH on renal production of 1,25(OH)2D in SH rats before (4 weeks of age) and after (12 weeks of age) the onset of hypertension. Basal serum levels of 1,25(OH)2D were normal in SH rats at both ages. At 4 weeks of age, the rise in serum 1,25(OH)2D after PTH injection (50 units subcutaneously every 2 h; four times) was also normal in SH rats. By contrast, at 12 weeks of age, the rise in serum 1,25(OH)2D was approximately one-half of that in WKy rats, despite the similar rises in serum Ca2+ levels in both groups by PTH injection. The attenuated rise in serum 1,25(OH)2D in SH rats was consistent with the impaired response of renal 1-hydroxylase (25-hydroxycholecalciferol 1 alpha-hydroxylase) activity to PTH. Basal 1,25(OH)2D production by the kidney in SH rat was higher than that in WKy rats both at 4 and 12 weeks of age. These data suggest that, in SH rats: serum 1,25(OH)2D is inappropriately low in relation to the elevated PTH and this may be due, at least in part, to the impaired responsiveness to PTH of renal 1-hydroxylase and to the enhanced metabolism of 1,25(OH)2D, and elevated PTH or other agents may stimulate the 1-hydroxylase in the kidney even before the onset of hypertension.
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PMID:Altered vitamin D metabolism in the kidney of the spontaneously hypertensive rat. 380 Sep 24

We have reported that cytochrome P-450-dependent omega-hydroxylation of arachidonic acid is reduced in microsomes prepared from the renal outer medulla of Dahl salt-sensitive (SS/Jr) rats, but the functional significance of this observation is unknown. The present study examined whether long-term induction of renal fatty acid omega-hydroxylase with clofibrate would alter the development of hypertension in Dahl SS/Jr rats. Dahl SS/Jr rats were placed on a high salt diet (8.0% NaCl) and given either vehicle or clofibrate (80 mg/day) in their drinking water. After 4 weeks of a high salt diet, mean arterial pressure averaged 170 +/- 3 mm Hg in vehicle-treated (n = 17) and 127 +/- 2 mm Hg in clofibrate-treated (n = 19) SS/Jr rats. Clofibrate had no effect on arterial pressure in Dahl salt-resistant rats. The antihypertensive effect of clofibrate was reversible. Mean arterial pressure rose from 131 +/- 4 to 182 +/- 8 mm Hg in the first week after clofibrate treatment (n = 6) was discontinued. Clofibrate had no effect on arterial pressure in SS/Jr rats (n = 9) in which hypertension was already established by feeding the rats a high salt diet for 4 weeks before the study. In clofibrate-treated SS/Jr rats (n = 12), the omega-hydroxylation of arachidonic and lauric acids by renal cortical and outer medullary microsomes was greater than that seen in vehicle-treated rats (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1993 Jun
PMID:Clofibrate prevents the development of hypertension in Dahl salt-sensitive rats. 850 11

The present study evaluated the contribution of cytochrome P-450 omega-hydroxylase in modulating the reactivity of cremaster muscle arterioles in normotensive rats on high-salt (HS) and low-salt (LS) diet and in rats with reduced renal mass hypertension (RRM-HT). Changes in arteriolar diameter in response to ACh, sodium nitroprusside (SNP), ANG II, and elevated O(2) were measured via television microscopy under control conditions and following cytochrome P-450 omega-hydroxylase inhibition with 17-octadecynoic acid (17-ODYA) or N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS). In normotensive rats on either LS or HS diet, resting tone was unaffected and arteriolar reactivity to ACh or SNP was minimally affected by cytochrome P-450 omega-hydroxylase inhibition. In RRM-HT rats, cytochrome P-450 omega-hydroxylase inhibition reduced resting tone and significantly enhanced arteriolar dilation to ACh and SNP. Treatment with 17-ODYA or DDMS inhibited arteriolar constriction to ANG II and O(2) in all the groups, although the degree of inhibition was greater in RRM-HT than in normotensive animals. These results suggest that metabolites of cytochrome P-450 omega-hydroxylase contribute to the altered reactivity of skeletal muscle arterioles to vasoconstrictor and vasodilator stimuli in RRM-HT.
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PMID:Contribution of cytochrome P-450 omega-hydroxylase to altered arteriolar reactivity with high-salt diet and hypertension. 1077 29

We tested the hypothesis that cyclooxygenase-independent vasodilation produced by arachidonic acid (AA) is mediated by epoxyeicosatrienoic acids (EETs) and is blunted in the spontaneously hypertensive rat (SHR). At normal perfusion pressure (PP; 70 to 90 mm Hg), AA constricted the renal vasculature in both SHR and normotensive Wistar-Kyoto rats, an effect abolished by cyclooxygenase inhibition, and converted to vasodilation when PP was raised to approximately 200 mm Hg. Unexpectedly, renal vasodilation elicited by AA was greater in the SHR at high PP; for example, 2.5, 5, and 10 microg of AA produced PP declines of 54+/-9, 92+/-10, and 112+/-5 mm Hg, respectively, in SHR compared with 26+/-3, 45+/-5, and 77+/-6 mm Hg in Wistar-Kyoto rats (P:<0.01). However, the renal vasodilator responses to acetylcholine (0.1 microg) and sodium nitroprusside (1 microg) did not differ between strains, indicating that vascular responsiveness to AA was independent of intrinsic changes in vascular smooth muscle. Hyperresponsiveness of the renal vasculature to AA may be unique for the SHR, because it did not occur in Sprague-Dawley rats with angiotensin II-induced hypertension. 5,8,11,14-Eicosatetraynoic acid (ETYA; 4 micromol/L), an inhibitor of all AA pathways, attenuated the vasodilator responses to AA, as did treatment with stannous chloride, which depletes cytochrome P450 enzymes, suggesting that a cytochrome P450 AA metabolite mediated the renal vasodilation. N:-Methylsulfonyl-12,12-dibromododec-11-en-amide (DDMS; 2 micromol/L), a selective omega-hydroxylase inhibitor, did not affect AA-induced vasodilation, whereas selective inhibition of epoxygenases with either miconazole (0.3 micromol/L) or N:-methylsulfonyl-6-(2-propargyloxyphenyl) hexanamide (MS-PPOH; 12 micromol/L) did, indicating that one or more EETs were involved in the renal vasodilator action of AA at high PP. This conclusion was supported by the demonstration that AA greatly enhanced the renal efflux of EETs at high PP but not at basal PP.
Hypertension 2001 Mar
PMID:Epoxyeicosatrienoic acid-mediated renal vasodilation to arachidonic acid is enhanced in SHR. 1124 13

Since the initial reports that renal cytochrome P450 (CYP) enzymes can metabolize arachidonic acid to substances which affect arterial tone, it has become increasingly clear that CYP enzymes expressed within the cardiovascular system play a crucial role in the modulation of vascular homeostasis. There is strong evidence suggesting that the activation of a CYP epoxygenase in endothelial cells is an essential step in nitric oxide and prostacyclin-independent vasodilatation of several vascular beds, particularly in the heart and kidney. A smooth muscle CYP omega-hydroxylase, on the other hand, generates a vasoconstrictor eicosanoid that is central to the myogenic response. Moreover, CYP epoxygenase and omega-hydroxylase products, as well as CYP-derived reactive oxygen species, are intracellular signal transduction molecules involved in several signaling cascades affecting numerous cellular processes, including vascular cell proliferation and angiogenesis. This review summarizes the vascular effects of epoxyeicosatrienoic acids and 20-hydroxyeicosatetraenoic acid, both of which are CYP-derived metabolites of arachidonic acid, endogenously generated within endothelial and vascular smooth muscle cells. Although the link between CYP expression/activity and cardiovascular disease is currently tentative, the evidence being accumulated to suggest that CYP pathways are altered in animal models of hypertension and atherosclerosis can no longer be ignored. The development of selective pharmacological tools is, however, a prerequisite for the analysis of the involvement of specific CYP isoforms in the regulation of vascular homeostasis in human subjects.
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PMID:Cytochrome p450 and vascular homeostasis. 1167 4

The incidence of essential hypertension increases with obesity; however, the mechanisms that link obesity with hypertension are unclear. Renal cytochrome P450 (CYP)-derived eicosanoids--hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatrienoic acids (EETs), and dihydroxyeicosatrienoic acids (DHETs)--have been shown to play an important role in the regulation of renal function, vascular tone, and blood pressure. The objective of this study was to examine CYP-derived eicosanoid synthesis in the different renal zones (cortex, medulla, and papilla) of rats fed a high fat diet (HF). Male Sprague-Dawley rats were fed a HF diet or regular rat chow for 10 weeks. After 10 weeks, HF rats showed significantly higher systolic blood pressure, body weight, and fat:body weight ratio. The renal omega-hydroxylase activity was decreased by 46% in cortex, 43% in medulla, and 46% in papilla of HF rats. The renal epoxygenase activity was decreased by 46% in cortex, 31% in medulla, and 56% in papilla of HF rats. Interestingly, the changes in the rate of 20-HETE and EET formation in different renal zones were consistent with the levels of expression of CYP4A and CYP2C23 proteins, respectively. Furthermore, there were no significant changes in the synthesis of these metabolites in the renal microvessels. These results demonstrate that HF diet causes the downregulation of CYP4A and CYP2C23 in renal tubules, and these proteins are responsible for renal 20-HETE and EET formation. The reduction in the synthesis of these eicosanoids may play an important role in the regulation of renal function and blood pressure in obesity-induced hypertension.
Hypertension 2003 Oct
PMID:Downregulation of renal CYP-derived eicosanoid synthesis in rats with diet-induced hypertension. 1293 36

Epoxyeicosatrienoic acids (EETs), which belong to cytochrome P-450 (CYP)-derived eicosanoids, have been implicated to vasodilate renal arterioles, inhibit sodium transport in the nephron, and regulate blood pressure in several animal models. Because pregnancy is associated with changes of blood pressure, the aim of this study was to examine whether renal EET synthesis is altered and whether EETs are involved in blood pressure regulation during pregnancy in rats. Renal microsomal epoxygenase activity increased by 47, 97, and 63% on days 6, 12, and 19 of gestation, respectively. The elevation of epoxygenase activity during pregnancy was associated with an increase in CYP2C11, CYP2C23, and CYP2J2 protein expression on days 6, 12, and 19 of gestation. Moreover, immunohistochemical analysis showed that renal tubular CYP2C11, CYP2C23, and CYP2J2 expression was significantly increased in pregnant rats on days 6, 12, and 19 of gestation. Administration of 6-(2-propargyloxyphenyl)hexanoic acid (PPOH), a selective epoxygenase inhibitor, caused a dose-dependent inhibition of microsomal expoxygenase activity without a significant effect on omega-hydroxylase activity in female rats. Interestingly, administration of PPOH (20 mg.kg(-1).day(-1) for 4 days starting on day 15 of pregnancy) increased blood pressure by 21 mmHg and caused a significant decrease in the body weight of fetal pups (1.3 +/- 0.08 g in control vs. 1.1 +/- 0.06 g in PPOH). Moreover, PPOH treatment significantly decreased renal microsomal epoxygenase activity and the expression of CYP2C11, CYP2C23, and CYP2J in pregnant rats. This study demonstrates that EET synthesis in the kidney is elevated during pregnancy, and CYP2C11, 2C23, and CYP2J2 are responsible for the change of renal EET synthesis. The inhibition results demonstrate that the downregulation of renal epoxygenase activity by PPOH causes hypertension in pregnant rats. This study suggests that EETs may contribute to the control of blood pressure during pregnancy.
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PMID:Renal epoxyeicosatrienoic acid synthesis during pregnancy. 1538 99

The soluble epoxide hydrolase (sEH) metabolizes vasodilatory epoxyeicosatrienoic acids (EETs) to their di-hydroxy derivatives. We hypothesized that the metabolism of EETs by the sEH contributes to angiotensin II-induced hypertension and tested the effects of a water-soluble sEH inhibitor, 12-(3-adamantan-1-yl-ureido) dodecanoic acid (AUDA) on blood pressure. AUDA (130 microg/mL in drinking water) did not affect blood pressure in normotensive animals but markedly lowered it in mice with angiotensin II-induced hypertension (1 mg/kg per day). The effect of AUDA was accompanied by an increase in urinary salt and water excretion. Intravenous application of AUDA (8 mg/kg) acutely lowered blood pressure and heart rate in animals with angiotensin II-induced hypertension but failed to affect blood pressure in animals with phenylephrine-induced hypertension (29 mg/kg per day). AUDA (0.1 micromol/L) selectively lowered vascular resistance in an isolated perfused kidney preparation from angiotensin II-pretreated mice but not from control mice. In the perfused hind limb and in isolated carotid arteries from angiotensin II-treated mice, AUDA was without effect. The omega-hydroxylase inhibitor N-methylsulfonyl-12,12-dibromododec-11-enamide, which attenuates formation of the potent vasoconstrictor 20-hydroxyeicosatetraenoic acid, decreased tone in carotid arteries from angiotensin II-treated but not from control mice. These data demonstrate that the decrease in blood pressure observed after sEH inhibition in angiotensin II-induced hypertension can be attributed to an initial reduction in heart rate followed by pressure diuresis resulting from increased perfusion of the kidney. Direct vasodilatation of resistance arteries in skeletal muscles does not appear to contribute to the antihypertensive effects of sEH inhibition in mice.
Hypertension 2005 Apr
PMID:Soluble epoxide hydrolase is a main effector of angiotensin II-induced hypertension. 1569 57

Previous studies suggested an important role for 20-HETE in the regulation of myogenic responses. Thus, pressure-diameter relationships were investigated in isolated, cannulated coronary arteries (approximately 100 microm) from male endothelial NO synthase knockout (eNOS-KO) and wild-type (WT) mice. All arteries constricted in response to step increases in perfusate pressure from 20 to 100 mm Hg. This constriction was significantly enhanced from 40 to 100 mm Hg in arteries of eNOS-KO compared with those of WT mice. For example, at 60 and 100 mm Hg, respectively, the normalized diameter (expressed as a percentage of the corresponding passive diameter) of arteries of eNOS-KO mice was 10% and 12% smaller than that of WT mice. Removal of the endothelium did not significantly affect the responses of vessels from either strain of mice. However, N-methylsulfonyl-12,12-dibromododec-11-enamide (5x10(-6) M), an inhibitor of cytochrome P-450 (CYP)/omega-hydroxylase, significantly attenuated the greater myogenic constriction of arteries from eNOS-KO mice by approximately 12% at each pressure step but did not significantly affect responses of those from WT mice, leading to a comparable myogenic response in the 2 strains. Western blot analysis demonstrated a comparable CYP4A protein content in coronary arteries of the 2 strains of mice. However, production of 20-HETE, measured by fluorescent high-performance liquid chromatography assay was approximately 2.7-fold greater in eNOS-KO compared to WT mice. Thus, as a function of eNOS deficiency, the enhanced coronary artery constriction to pressure is attributable to an increased activity of omega-hydroxylase, which, consequently, increases the synthesis of 20-HETE in vascular smooth muscle.
Hypertension 2005 Sep
PMID:Contribution of 20-HETE to augmented myogenic constriction in coronary arteries of endothelial NO synthase knockout mice. 1604 60

Alcohol-induced hypertension is well recognized with clear evidence for a direct pressor effect of chronic alcohol consumption provided by a number of intervention studies in humans. In experimental animals, the effect of alcohol on blood pressure is less consistent; however, in Sprague-Dawley rats, alcohol feeding consistently induces a hypertensive response. The mechanism of alcohol-induced hypertension is not clearly understood. Ethanol is known to induce certain cytochrome P450 (CYP) enzymes, particularly the 2E1 isoform, which has been shown to metabolise arachidonic acid (AA) to the 19-hydroxy metabolite (19-HETE), which could have pro-hypertensive activity; CYP4A, by comparison, is the principal AA omega-hydroxylase in the liver. Polyphenolic compounds, such as flavonoids, have been shown to inhibit some CYPs. 2. In this study, we determined the effect of alcohol administration on blood pressure and CYP-dependent AA metabolism in the rat and its possible modulation by red wine polyphenols. 3. Thirty male Sprague-Dawley rats were randomly allocated to three groups, which received water, low-dose ethanol (5% v/v) or red wine (diluted to contain 5% ethanol) for a period of 9 weeks. Bodyweight and blood pressure were measured weekly and 24h urine collected at baseline and every 2 weeks. Animals were killed at 9 weeks and blood and tissue samples were collected. The blood pressure of rats fed with alcohol increased significantly over the period of the study compared with controls (P<0.001). The blood pressure of animals fed 5% alcohol in the form of red wine was not significantly different from controls over the study period. The urinary excretion of 20-HETE did not differ significantly among the treatment groups over the study period and there was no effect of any treatment on the metabolism of AA by renal microsomes. Red wine, but not administration of the relatively low dose of alcohol alone, increased the expression of CYP2E1 protein in the liver and kidney and CYP4A in the kidney. Both red wine and alcohol decreased CYP4A protein levels in the liver compared with controls. 4. Our results suggest that constituents of red wine, possibly polyphenols, can attenuate the alcohol-induced rise in blood pressure in the Sprague-Dawley rat, although this effect does not appear to be mediated by the inhibition of CYP-derived AA metabolism.
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PMID:Effect of alcohol on cytochrome p450 arachidonic acid metabolism and blood pressure in rats and its modulation by red wine polyphenolics. 1648 60


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