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 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism and treatment of hypertensive systolic heart failure are not well defined. We compared the effect of an angiotensin-converting enzyme inhibitor (cilazapril, 10 mg/kg), an angiotensin receptor blocker (candesartan, 3 mg/kg), a calcium channel blocker (benidipine, 1, 3 or 6 mg/kg), and the same calcium channel blocker combined with renin-angiotensin blockers on systolic heart failure in Dahl salt-sensitive (DS) rats. DS rats were fed an 8% Na diet from 6 weeks of age and then subjected to the above drug treatments. Benidipine (1 mg/kg), cilazapril, and candesartan had compatible hypotensive effects and similar beneficial effects on cardiac hypertrophy, gene expression, and survival rate. The combination of benidipine with cilazapril or candesartan was found to have no additional beneficial effects on the above parameters, with the exception of a reduction in atrial natriuretic polypeptide gene expression. On the other hand, candesartan normalized serum creatinine, but serum creatinine was unaffected by either benidipine at 1 or 3 mg/kg or cilazapril. Further, the combined use of benidipine and either candesartan or cilazapril resulted in an additional reduction of urinary albumin excretion in DS rats. Thus systolic heart failure in DS rats is mainly mediated by hypertension, while renal dysfunction of DS rats is due to both hypertension and the AT1 receptor itself. These findings suggest that the combination of a calcium channel blocker with an AT1 receptor blocker or ACE inhibitor may be more effective in treating the renal dysfunction associated with systolic heart failure than monotherapy with either agent alone. However, further studies will be needed before reaching any definitive conclusion on the efficacy of this combination therapy in patients with heart failure.
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PMID:Combination treatment with a calcium channel blocker and an angiotensin blocker in a rat systolic heart failure model with hypertension. 1213 27

Regulation of the expression of the klotho gene, which suppresses the expression of multiple aging-associated phenotypes, by angiotensin II was investigated. Continuous infusion of angiotensin II downregulated renal klotho gene expression, which was an AT1 receptor-dependent, but pressor-independent event. In some experiments, adenovirus harboring mouse klotho gene(ad-klotho, 3.3 x 10(10) pfu) was intravenously administered immediately before starting angiotensin II infusion, and this resulted in an improvement of creatinine clearance, decrease in urinary protein excretion, and amelioration of tubulointerstitial damage induced by this octapeptitde. Downregulation of the renal klotho gene may have a role in the development of angiotensin II-induced end organ damage.
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PMID:[Angiotensin II regulates klotho gene expression]. 1239 87

Treatment of rats with streptozotocin (STZ, 45mg/kg, i.v.,single dose) produced cardinal symptoms of diabetes mellitus including hyperglycemia, hypoinsulinemia and increase in blood pressure. Treatment with losartan--an angiotensin (AT1) receptor antagonist, 2 mg/kg, po for 6 weeks decreased the blood glucose levels by 16.5%. There was 190% increase in AUCglucose and 59.4% decrease in AUCinsulin in STZ-diabetic rats as compared to control rats. Treatment with losartan caused slight decrease in AUCglucose and slight increase in AUCinsulin. There was no significant difference in insulin sensitivity (K(ITT)) index of STZ-diabetic group as compared to control. Losartan treatment failed to alter these levels significantly. Serum cholesterol and creatinine levels were found to be increased significantly in STZ-diabetic rats. Treatment with losartan significantly prevented the rise in cholesterol and creatinine levels by 20.1 and 81% respectively. The results suggest that losartan produces some beneficial effects in STZ-diabetic rats.
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PMID:Effect of chronic treatment with losartan on streptozotocin induced diabetic rats. 1256 64

Renal fibrosis is one of the major complications associated with the development of hypertension. The objective of the present study was to determine whether and by which mechanisms treatment with AT1 receptor antagonists makes possible the regression of renal vascular and glomerular fibrosis. Experiments were performed in the hypertensive model of nitric oxide (NO) deficiency in rats. After 4 wk of hypertension, mortality rates averaged 20%; the surviving animals displayed a decline of renal function (urine protein/creatinine, 1.89 +/- 0.63 versus 0.24 +/- 0.03 mg/mmol; creatininemia, 110 +/- 14 versus 38 +/- 2 mmol/L in hypertensive animals and control, respectively; P < 0.01) and an exaggerated gene and protein expression of TGF-beta, collagen I, and collagen IV (P < 0.001) within the renal vasculature associated with the development of glomerulosclerosis (sclerotic index, 2.26 +/- 0.29 versus 0.12 +/- 0.04; P < 0.001). In addition, activities of matrix metalloproteinases 2 and 9 were increased twofold in renal vessels and glomeruli (P < 0.01). Afterwards, losartan, an antagonist of angiotensin receptor type I, or hydralazine were administered in subgroups of hypertensive animals. After 1 wk of angiotensin II antagonism, collagen I, collagen IV, and TGF-beta gene and protein expressions were decreased and glomerulosclerosis was less marked (sclerotic index 1.04 +/- 0.45), whereas activities of metalloproteinases remained twofold higher than controls (P < 0.01). Hydralazine failed to improve renal function despite a similar degree of systolic pressure decrease. After 4 wk of losartan, the renal functional and histologic parameters were completely normalized, whereas they remained damaged in the hypertensive animals in which the mortality rate reached 85%. These data suggest that the progression of renal vascular fibrosis is a reversible process, at least in the NO deficiency model. The mechanism of the regression appears to be dual: inhibition of collagen synthesis due to AT1 receptor antagonism and activation of metalloproteinases that is probably associated with the degree of fibrosis independently of AT1 blockade.
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PMID:Regression of renal vascular and glomerular fibrosis: role of angiotensin II receptor antagonism and matrix metalloproteinases. 1270 11

In Germany, 36% of all new chronic dialysis patients have diabetic nephropathy. The majority are type 2 diabetics. Early intervention has the greatest effect. Incipient nephropathy can be diagnosed by evidence of microalbuminuria (30-300 mg albumin/g creatinine). Proteinuria on the standard test strip (>300 mg/g) indicates manifest nephropathy followed by progressive renal failure. Important cofactors for progression are hypertension, hyperglycemia, and smoking. Low normal blood pressure levels (<130/80 mmHg without and <125/75 mmHG with proteinuria) based on ACE inhibitors/AT1 blockers are the goal. Combination therapies are frequently necessary. This can often reverse microalbuminuria. Chronic renal failure requires special attention (e.g. bone metabolism, anemia, acidosis). Timely initiation of renal replacement therapy (GFR <15 ml/min) reduces morbidity and mortality. In addition to hemo- and peritoneal dialysis, early kidney and in individual cases of type 1 diabetes combined kidney/pancreas transplantation is appropriate.
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PMID:[Diagnostics and therapy of diabetic nephrology]. 1273 10

The present investigation was undertaken to study the effect of chronic treatment with angiotensin (AT1) receptor antagonist losartan (2 mg/kg, p.o., 6 weeks) on streptozotocin (STZ) induced (45 mg/kg, i.v., single dose) renal dysfunctions in diabetic rats. Injection of streptozotocin produced not only the cardinal symptoms of diabetes mellitus like loss of body weight, hyperglycemia, and hypoinsulinemia but also the renal dysfunctions. Losartan treatment significantly prevented all these changes except STZ-induced hypoinsulinemia. There was a significant elevation of blood pressure in diabetic rats and treatment with losartan significantly brought it back to normal. Renal dysfunction in diabetic rats was characterized by a significant decrease in creatinine clearance, elevated levels of electrolytes and renal hypertrophy. Treatment with losartan prevented these changes. A good correlation was found between biochemical parameters and histopathological abnormalities. Our data suggests that, losartan may be considered as the drug of choice when there is a co-existence of diabetes mellitus and hypertension with compromised kidney function.
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PMID:Effect of chronic treatment with losartan on streptozotocin-induced renal dysfunction. 1295 2

Hyperhomocysteinemia is associated with an enhanced risk for cardiovascular disease. Patients with peripheral arterial disease (PAD) show an increased prevalence of hyperhomocysteinemia. A decreased biological activity of nitric oxide (NO) may contribute to homocysteine-associated endothelial dysfunction. This study was designed to investigate whether elevated levels of the endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) are involved in endothelial dysfunction in patients with chronic hyperhomocysteinemia and PAD. A total of 76 patients (58 males and 18 females; mean age 65.2 +/- 2.0 years) with PAD were included in the analysis and characterized according to demographic variables and cardiovascular risk factors. Flow-dependent vasodilation (FDD) was determined by high-resolution ultrasound in the radial artery. Total plasma homocysteine (plasma tHcy) and ADMA levels were measured by HPLC. Urinary nitrate was quantified using gas chromatography-mass spectrometry. Patients with plasma tHcy in the highest tertile (n = 27; i.e. > 10.6 micromol/l) had a mean plasma level of 14.4 +/- 1.21 mol/l compared with 9.9 +/- 0.1 micromol/l in those patients in the middle tertile (n = 22; p < 0.05) and 9.4 +/- 0.1 micromol/l in those in the lowest tertile (n = 27; i.e. <9.6 micromol/l; p < 0.05). The hyperhomocysteinemic individuals (highest tertile) had a significantly decreased FDD compared with healthy age-matched controls (n = 15) (7.6 +/- 1.0 vs 13.0 +/- 0.4%; p < 0.05), higher plasma ADMA concentrations (4.0 +/- 0.3 vs 2.6 +/- 0.3 micromol/l; p < 0.05), and a lower urinary nitrate excretion rate (89.5 +/- 13.4 vs 131.3 +/- 17.9 micromol/mmol creatinine; p < 0.05) compared with patients with plasma tHcy in the lowest tertile. Multivariate regression analysis including plasma tHcy, ADMA, total cholesterol, diabetes mellitus, smoking, and systolic blood pressure revealed ADMA as the only significant factor determining FDD (p < 0.05). In conclusion, we demonstrated a stronger relationship between impaired endothelial function and elevated ADMA levels in comparison with plasma tHcy concentrations in patients with PAD and chronic hyperhomocysteinemia. This may raise the question of whether different therapeutical options that interact indirectly with plasma tHcy, i.e. treatment with ACE inhibitors and AT1-receptor blockers to reduce ADMA plasma concentrations or L-arginine, could be a beneficial tool for treating patients with hyperhomocysteinemia.
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PMID:Endothelial dysfunction in patients with peripheral arterial disease and chronic hyperhomocysteinemia: potential role of ADMA. 1552 98

Cyclosporine A (CsA), a fungal undecapeptide, is the most common immunosuppressive drug used in organ transplantation and autoimmune diseases. However, nephrotoxicity is the major adverse effect of CsA use. The molecular mechanisms of CsA nephrotoxicity are not well characterized, but more recent studies suggest an involvement of angiotensin II (ANG II) and reactive oxygen species in the development of cyclosporine nephrotoxicity. Induction of heat shock proteins (HSPs) is one of the best-described cellular responses to heat stress, hypoxia, and exposure to oxidants. HSPs have beneficial roles in protein processing and protection against cell injury. There is emerging evidence that ANG II induces oxidative stress in vitro and in vivo. This study was thus designed to investigate the role of Angiotensin II type I (AT1) receptor antagonist, irbesartan, on CsA-induced nephrotoxicity. Five groups of rats were employed in this study: group 1 served as control, group 2 rats were treated with CsA (20 mg kg(-1), subcutaneously for 21 days), and groups 3, 4, and 5 received CsA along with irbesartan (10, 25, and 50 mg kg(-1), perorally 24 hr before and 21 days concurrently), respectively. Renal function was assessed by measuring serum creatinine, blood urea nitrogen, creatinine, and urea clearance. The renal oxidative stress was measured by renal malondialdehyde levels, reduced glutathione levels, and enzymatic activity of catalase, glutathione reductase, and superoxide dismutase. Renal morphological alterations were assessed by histopathological examination. CsA administration for 21 days resulted in a marked renal oxidative stress and significantly deranged the renal functions as well as renal morphology. All these factors were significantly improved by irbesartan (50 mg kg(-1)) treatment. HSP72, HSP47, and HSP25 were clearly induced and expressed in CsA-treated animals. The induction and expression of HSP25 was markedly protected by treatment with irbesartan, whereas the induction and expression of HSP47 and HSP72 remained unaltered with the irbesartan treatment. These results clearly demonstrate the pivotal role of ANG II-induced oxidative stress and therapeutic potential of AT, receptor antagonist in ameliorating CsA-induced nephrotoxicity.
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PMID:Amelioration of cyclosporine nephrotoxicity by irbesartan, A selective AT1 receptor antagonist. 1552 4

Recent studies have shown that F2-isoprostane levels-a marker for lipid peroxidation-are increased in human renovascular hypertension but not in essential hypertension. Angiotensin II specifically stimulates F2-isoprostane production through activation of the AT1 receptor. The objective was to determine whether there is a relationship between the level of oxidative stress evaluated by measuring urinary F2-isoprostanes levels and polymorphisms of genes involved in the renine angiotensin aldosterone system (RAAS) regulation. The population studied included 100 subjects, 65 of whom were healthy normotensives; the other 35 were suffering from untreated, essential hypertension. The polymorphisms studied concern the genes encoding angiotensin I-converting enzyme (ACE/in16del/ins), angiotensin II receptor type I (AGTR1/A+39C[A+1166C] and AGTR1/A-153G), angiotensinogen (AGT/M235T), and aldosterone synthase (CYP11B2/T344C). Oxidative stress was evaluated by measuring urinary F2-isoprostanes levels. The characteristics of the population were as follows: men/women = 46/56; age = 50 +/- 10 years; BMI = 24 +/- 3 kg/m2; SBP = 131.7 +/- 17.2 mm Hg; DBP = 84.6 +/- 10.4 mm Hg. In univariate analysis, urinary F2-isoprostane levels were significantly lower in the presence of the G allele of AGTR1/A-153G (56 +/- 17 vs 76 +/- 39 pmol/mmol creatinine; P < 0.001, and P < 0.01 after Bonferroni correction for 10 tests). In multivariate analysis, taking into account BP, age, gender, BMI, plasma glucose, and total cholesterol, the G allele of AGTR1/A-153G is linked independently to urinary F2-isoprostanes level (P < 0.01). Our data suggest that F2-isoprostane level depends at least in part on the A-153G polymorphism of the angiotensin II AT1 receptor gene. The clinical and prognostic relevance of this polymorphism requires further investigation.
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PMID:F2-Isoprostane level is associated with the angiotensin II type 1 receptor -153A/G gene polymorphism. 1568 14

Angiotensin II can induce oxidant stress by stimulating vascular superoxide production. Hypertension promotes mitochondrial function decline in brain, liver and heart. The aim of this study was to investigate whether a) hypertension is associated to kidney mitochondrial dysfunction, and b) angiotensin II blockade can reverse potential mitochondrial changes in hypertension. Four-month-old male spontaneously hypertensive rats (SHR) received drinking water containing candesartan (7.5 mg/kg/day, SHR+Cand), or no additions (SHR) for 4-months. Eight-month-old Wistar-Kyoto rats (WKY), that received water with no additions, were used as control. Systolic blood pressure, proteinuria, cortical glomerular area, and glomerular and tubulointerstitial alpha-smooth muscle actin labeling, were significantly higher, and creatinine clearance was significantly lower, in SHR relative to WKY and SHR+Cand. In SHR, kidney mitochondria membrane potential, and nitric oxide synthase and cytochrome oxidase activities were significantly lower than in WKY and SHR+Cand. In SHR, mitochondrial hydrogen peroxide production was significantly higher than in WKY and SHR+Cand. The results suggest that, in hypertension, increased mitochondrial oxidant production may mediate kidney mitochondria dysfunction. Candesartan preserved mitochondrial function, probably favoring the maintenance of adequate cellular and tissue function in the kidney. The known renal protective effects of candesartan in hypertension may be related to the improvement of mitochondrial function. This may be an additional or alternative explanation for some of the beneficial effects of AT1 receptor antagonists.
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PMID:Angiotensin II blockade improves mitochondrial function in spontaneously hypertensive rats. 1630 82


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