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)

It remains open to debate whether hyperinsulinemia leads to the development of hypertension. We addressed this issue by investigating the effect of chronic insulin infusion on blood pressure and related parameters in hypertensive fructose-fed rats. Rats were given either normal chow or a fructose-rich diet, and insulin or saline was infused through mini-pumps in the same animals for 14 days. The chronic insulin infusion exerted no effect on the blood pressure of the chow-fed rats. Fructose feeding increased the blood pressure and levels of insulin, triglyceride and fatty acid. Insulin infusion augmented the hyperinsulinemia but normalized the blood pressure and plasma lipids. Plasma angiotensin II was elevated in the fructose-fed rats, while insulin infusion left it unchanged. The expression of angiotensin II type 1 receptor (AT1R) mRNA was doubled in both the aorta and epididymal fat of the fructose-fed rats, while that of angiotensin II type 2 receptor (AT2R) was unaltered. Insulin infusion completely rectified the over-expression of the AT1R gene. Our findings indicate that chronic insulin infusion exacerbates hyperinsulinemia while normalizing blood pressure and the gene expressions of AT1R in insulin-resistant fructose-fed rats, suggesting that endogenous hyperinsulinemia caused by insulin resistance is associated with the development of hypertension, whereas exogenous hyperinsulinemia attenuates hypertension probably due to amelioration of insulin resistance.
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PMID:Chronic insulin infusion normalizes blood pressure and the gene expressions of angiotensin II type 1 receptor in fructose-fed rats. 1836 27

The renin-angiotensin system is a far more complex enzymatic cascade than realized previously. Mounting evidence suggests sex-specific differences in the regulation of the renin-angiotensin system and arterial pressure. We examined the hemodynamic responses, angiotensin II receptor subtypes, and angiotensin-converting enzyme 2 gene expression levels after graded doses of angiotensin II in males and females. Mean arterial pressure was measured via telemetry in male and female rats in response to a 2-week infusion of vehicle, low-dose (50 ng/kg per minute SC) or high-dose (400 ng/kg per minute SC) angiotensin II. The effect of concurrent infusion of the angiotensin II type 2 receptor (AT(2)R) blocker (PD123319) was also examined. The arterial pressure response to high-dose angiotensin II was attenuated in females compared with males (24+/-8 mm Hg versus 42+/-5 mm Hg; P for the interaction between sex and treatment <0.002). Remarkably, low-dose angiotensin II decreased arterial pressure (11+/-4 mm Hg; P for the interaction between sex and treatment <0.02) at a dose that did not have an effect in males. This decrease in arterial pressure in females was abolished by AT(2)R blockade. Renal AT(2)R, angiotensin-converting enzyme 2, and left ventricular AT(2)R mRNA gene expressions were markedly greater in females than in males with a renal angiotensin II type 1a receptor:AT(2)R ratio of approximately 1 in females. Angiotensin II infusion did not affect renal AT(2)R mRNA expression but resulted in significantly less left ventricular mRNA expression. Renal angiotensin-converting enzyme 2 mRNA expression levels were greater in females than in males treated with high-dose angiotensin II (approximately 2.5 fold; P for the interaction between sex and treatment <0.05). In females, enhancement of the vasodilatory arm of the renin-angiotensin system, in particular, AT(2)R and angiotensin-converting enzyme 2 mRNA expression, may contribute to the sex-specific differences in response to renin-angiotensin system activation.
Hypertension 2008 Oct
PMID:Enhanced angiotensin II type 2 receptor mechanisms mediate decreases in arterial pressure attributable to chronic low-dose angiotensin II in female rats. 1893 41

Upregulation of angiotensin II type 1 receptors (AT(1)R) in the rostral ventrolateral medulla (RVLM) contributes to the sympathoexcitation in the chronic heart failure (CHF). However, the role of angiotensin II type 2 receptor (AT(2)R) is not clear. In this study, we measured AT(1)R and AT(2)R protein expression in the RVLM and determined their effects on renal sympathetic nerve activity, blood pressure, and heart rate in anesthetized sham and CHF rats. We found that (1) although AT(1)R expression in the RVLM was upregulated, the AT(2)R was significantly downregulated (CHF: 0.06+/-0.02 versus sham: 0.15+/-0.02, P<0.05); (2) simultaneously stimulating RVLM AT(1)R and AT(2)R by angiotensin II evoked sympathoexcitation, hypertension, and tachycardia in both sham and CHF rats with greater responses in CHF; (3) stimulating RVLM AT1R with angiotensin II plus the specific AT(2)R antagonist PD123319 induced a larger sympathoexcitatory response than simultaneously stimulating AT(1)R and AT(2)R in sham rats, but not in CHF; (4) activating RVLM AT(2)R with CGP42112 induced a sympathoinhibition, hypotension, and bradycardia only in sham rats (renal sympathetic nerve activity: 36.4+/-5.1% of baseline versus 102+/-3.9% of baseline in artificial cerebrospinal fluid, P<0.05); (5) pretreatment with 5,8,11,14-eicosatetraynoic acid, a general inhibitor of arachidonic acid metabolism, into the RVLM attenuates the CGP42112-induced sympathoinhibition. These results suggest that AT(2)R in the RVLM exhibits an inhibitory effect on sympathetic outflow, which is, at least partially, mediated by an arachidonic acid metabolic pathway. These data implicate a downregulation in the AT(2)R as a contributory factor in the sympathoexcitation in CHF.
Hypertension 2008 Oct
PMID:Imbalance of angiotensin type 1 receptor and angiotensin II type 2 receptor in the rostral ventrolateral medulla: potential mechanism for sympathetic overactivity in heart failure. 1876 98

Increased angiotensinogen (AGT) production by white adipose tissue has been related to not only obesity but also hypertension. Several studies have highlighted the importance of the angiotensin II type 2 receptor (AT2) in the regulation of blood pressure and fat mass, but the relevance of this transporter in a physiopathological model of increased AGT production, as it occurs in obesity, has not yet been investigated. We used transgenic mice that display either a deletion of AT2 (AT2 KO), an overexpression of AGT (OVEX), or both compound mutants (KOVEX). Results demonstrated that adipocyte hypertrophy and increased lipogenic gene expression induced by adipose AGT overproduction was rescued by deletion of AT2. In line with AGT overexpression, KOVEX and OVEX mice have similar increased plasma AGT levels. However, KOVEX mice display a higher blood pressure than OVEX mice. In kidney, renin expression was clearly reduced in OVEX mice, and its expression was normalized in KOVEX mice. Taken together, we demonstrated that the loss of AT2 expression was sufficient to rescue obesity induced by adipose tissue AGT overexpression and confirmed the necessary role of AT2 for the onset of obesity in this model. Furthermore, despite a reduction of adipose mass in KOVEX, AT2 deficiency caused increased renin production, further worsening the hypertension caused by AGT overexpression.
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PMID:Deficiency of angiotensin type 2 receptor rescues obesity but not hypertension induced by overexpression of angiotensinogen in adipose tissue. 1894 99

Recently we have cloned angiotensin II type 2 receptor-interacting protein 1 (ATIP1) as a novel protein that interacts specifically with the C-terminal tail of the angiotensin II type 2 receptor; however, the pathophysiological roles of ATIP1 in vascular remodeling are still unknown. Here, we generated ATIP1-transgenic (ATIP1-Tg) mice expressing mouse ATIP1 and investigated the role of ATIP1 in vascular remodeling using these transgenic mice. ATIP1-Tg mice exhibited no significant difference in blood pressure compared with wild-type (WT) mice. Angiotensin II type 2 receptor mRNA expression in the femoral artery was increased in injured femoral arteries, reaching a peak at 7 days after operation in WT mice, and a similar result of angiotensin II type 2 receptor expression was observed in ATIP1-Tg mice. In ATIP1-Tg mice, neointimal formation of the femoral artery 14 days after cuff placement was significantly smaller than that in WT mice. 5-Bromo-2'-deoxyuridine incorporation was significantly reduced in the injured arteries of ATIP1-Tg mice compared with WT mice. In ATIP1-Tg mice, superoxide anion production and the expression of a proinflammatory cytokine, tumor necrosis factor-alpha, were markedly attenuated. Moreover, cell proliferative signaling, such as extracellular signal-regulated kinase phosphorylation, was significantly attenuated in ATIP1-Tg mice compared with WT mice. Taken together, these results suggest that ATIP1 plays an important role in cuff-induced vascular remodeling in mice.
Hypertension 2009 Apr
PMID:Attenuation of cuff-induced neointimal formation by overexpression of angiotensin II type 2 receptor-interacting protein 1. 1922 Dec 7

OBJECTIVE Recent studies have proven the favorable effects of angiotensin receptor blockers (ARBs) on cardiovascular and renal disorders. However, determinants of the response to ARBs remain unclear. We substantiated the hypothesis that genetic variants of the renin-angiotensin system (RAS) have significant impacts on the response to ARBs. RESEARCH DESIGN AND METHODS Subjects comprised 231 consecutively enrolled hypertensive individuals including 45 type 2 diabetic subjects. Five genetic variants of the RAS, i.e., renin (REN) C-5312T, ACE insertion/deletion, angiotensinogen M235T, angiotensin II type 1 receptor A1166C, and angiotensin II type 2 receptor C3123A were assayed by PCR and restriction fragment-length polymorphism. A dose of 40-160 mg/day of valsartan was administered for 3 months as a monotherapy. RESULTS Changes in diastolic blood pressure significantly differed between genotypes of REN C-5312T: 10.7-mmHg reduction (from 95.9 +/- 12.9 to 85.2 +/- 11.4) in CC versus 7.0-mmHg reduction (from 94.7 +/- 14.0 to 87.7 +/- 12.6) in CT/TT (P = 0.02 for interactive effects of valsartan and genotype). Responder rates also differed between the genotypes: 72.8% in CC versus 58.0% in CT/TT (P = 0.03). Univariate analysis indicated a significant association of response to valsartan with blood pressure, diabetes, plasma aldosterone concentration, and CC homozygotes of REN C-5312T. Finally, multiple logistic regression analysis revealed that systolic blood pressure, CC homozygotes of REN C-5312T, and diabetes were independent predictors for responders with odds ratios (95% CI) of 2.49 (1.41-4.42), 2.03 (1.10-3.74), and 0.48 (0.24-0.96), respectively. CONCLUSIONS This study provides strong support that a genetic variant of REN C-5312T and diabetes contribute to the effects of ARBs and are independent predictors for responder. Thus, in treatment of hypertension with ARBs, a new possibility for personalized medicine has been shown.
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PMID:Genetic variant of the Renin-Angiotensin system and diabetes influences blood pressure response to Angiotensin receptor blockers. 1950 12

In spite of recent advancements in the treatment of pulmonary hypertension, successful control has yet to be accomplished. The abundant presence of angiotensin-converting enzyme 2 (ACE2) in the lungs and its impressive effect in the prevention of acute lung injury led us to test the hypothesis that pulmonary overexpression of this enzyme could produce beneficial outcomes against pulmonary hypertension. Monocrotaline (MCT) treatment of mice for 8 weeks resulted in significant increases in right ventricular systolic pressure, right ventricle:left ventricle plus septal weight ratio, and muscularization of pulmonary vessels. Administration of a lentiviral vector containing ACE2, 7 days before MCT treatment prevented the increases in right ventricular systolic pressure (control: 25+/-1 mm Hg; MCT: 44+/-5 mm Hg; MCT+ACE2: 26+/-1 mm Hg; n=6; P<0.05) and right ventricle:left ventricle plus septal weight ratio (control: 0.25+/-0.01; MCT: 0.31+/-0.01; MCT+ACE2: 0.26+/-0.01; n=8; P<0.05). A significant attenuation in muscularization of pulmonary vessels induced by MCT was also observed in animals overexpressing ACE2. These beneficial effects were associated with an increase in the angiotensin II type 2 receptor:angiotensin II type 1 receptor mRNA ratio. Also, pulmonary hypertension-induced increases in proinflammatory cytokines were significantly attenuated by lentiviral vector-containing ACE2 treatment. Furthermore, ACE2 gene transfer in mice after 6 weeks of MCT treatment resulted in a significant reversal of right ventricular systolic pressure. These observations demonstrate that ACE2 overexpression prevents and reverses right ventricular systolic pressure and associated pathophysiology in MCT-induced pulmonary hypertension by a mechanism involving a shift from the vasoconstrictive, proliferative, and fibrotic axes to the vasoprotective axis of the renin-angiotensin system and inhibition of proinflammatory cytokines.
Hypertension 2009 Aug
PMID:Prevention of pulmonary hypertension by Angiotensin-converting enzyme 2 gene transfer. 1956 52

Angiotensin II is a vasoactive hormone of the renin-angiotensin system and plays an important role in the pathophysiology of several organ damages. Angiotensin II receptor blockers have been shown to be effective in treating both hypertension and connected organ damages. It is well known that although the angiotensin II receptor blockers have structural and pharmacokinetic differences, few pharmacological differences separate them. One of these is the degree of binding to the angiotensin II receptor type 1 compared with the angiotensin II receptor type 2; olmesartan medoxomil exhibits more than a 12,500-fold greater affinity for the angiotensin II receptor type 1 receptor than for the angiotensin II receptor type 2, making it theoretically the second most potent agent. However, olmesartan's excellent receptor interaction is based on the combination of several specific pharmacokinetic factors. Potential advantages of this drug include once-daily dosing, a very low incidence of significant adverse reactions and/or events and a well-tolerated side effect profile. Nowadays, we have a lot of information about the pharmacology, antihypertensive efficacy and safety of olmesartan medoxomil, to further extend many clinical studies are still continuing to evaluate the potential benefits of high dosages and/or combination of this molecule.
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PMID:Olmesartan medoxomil: recent clinical and experimental acquisitions. 1968 19

Angiotensin II has a key role in the control of resistance artery tone and local blood flow. Angiotensin II possesses 2 main receptors. Although angiotensin II type 1 receptor is well known and is involved in the vasoconstrictor and growth properties of angiotensin II, the role of the angiotensin II type 2 receptor (AT2R) remains much less understood. Although AT2R stimulation induces vasodilatation in normotensive rats, it induces vasoconstriction in pathological conditions involving oxidative stress and cyclooxygenase 2 expression. Thus, we studied the influence of cyclooxygenase 2 on AT2R-dependent tone in diabetes mellitus. Mesenteric resistance arteries were isolated from Zucker diabetic fatty (ZDF) and lean Zucker rats and studied using in vitro using wire myography. In ZDF rats, AT2R-induced dilation was lower than in lean rats (11% versus 21% dilation). Dilation in ZDF rats returned to the control (lean rats) level after acute superoxide reduction (Tempol and apocynin), cyclooxygenase 2 inhibition (NS398), or thromboxane A(2) synthesis inhibition (furegrelate). Cyclooxygenase 2 expression and superoxide production were significantly increased in ZDF rat arteries compared with arteries of lean rats. After chronic treatment with Tempol, AT2R-dependent dilation was equivalent in ZDF and lean rats. Chronic treatment of ZDF rats with NS398 also restored AT2R-dependent dilation to the control (lean rats) level. Plasma thromboxane B(2) (thromboxane A(2) metabolite), initially high in ZDF rats, was decreased by chronic Tempol and by chronic NS398 to the level found in lean Zucker rats. Thus, in type 2 diabetic rats, superoxide and thromboxane A(2) reduced AT2R-induced dilation. These findings are important to take into consideration when choosing vasoactive drugs for diabetic patients.
Hypertension 2010 Feb
PMID:Reactive oxygen species and cyclooxygenase 2-derived thromboxane A2 reduce angiotensin II type 2 receptor vasorelaxation in diabetic rat resistance arteries. 2002 67

Clinical and experimental studies have shown that the initial suppression of angiotensin II after the administration of angiotensin-converting enzyme (ACE) inhibitors is later reversed and returns almost to pretreatment levels. This raised the hypothesis of the "escape phenomenon," which was strengthened by the discovery that angiotensin II can also be generated through non-ACEs. Therefore, the addition of angiotensin receptor blockers to ACE inhibitors would produce additional benefits by blocking all angiotensin II at the angiotensin II receptor type 1 level and in addition allowing angiotensin II to stimulate the unoccupied angiotensin II receptor type 2, causing additional vasodilation and antiremodeling effects. However, analysis of various studies including hypertension, heart failure, and renal disease has demonstrated that the gain is modest when combining ACE inhibitors, angiotensin receptor blockers, or the renin blocker aliskiren. In conclusion, on the basis of the results of this analysis, dual blockade of the renin-angiotensin-aldosterone system should not be used for the treatment of hypertension, heart failure, and renal disease, with perhaps the exception of diabetic nephropathy with albuminuria, until additional information is provided from ongoing studies.
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PMID:Current status of dual Renin Angiotensin aldosterone system blockade for the treatment of cardiovascular diseases. 2021 30


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