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Stroke. 2008 Nov 20;
Inaba S, Iwai M, Tomono Y, Senba I, Furuno M, Kanno H, Okayama H, Mogi M, Higaki J, Horiuchi M
BACKGROUND AND PURPOSE: We examined the possibility that activation of the human brain renin-angiotensin system is involved in enhancement of ischemic brain damage using chimeric transgenic mice with human renin (hRN) and human angiotensinogen (hANG) genes. METHODS: Chimeric (hRN/hANG-Tg) mice were generated by mating of hRN and hANG transgenic mice. Permanent occlusion of the middle cerebral artery (MCA) by an intraluminal filament technique induced focal ischemic brain lesions. RESULTS: hRN/hANG-Tg mice showed higher angiotensin II levels in the plasma and brain. The ischemic brain area at 24 hours after MCA occlusion was significantly enlarged in hRN/hANG-Tg mice with an enhanced neurological deficit compared to that in wild-type, hRN-Tg and hANG-Tg mice. The reduction of cerebral blood flow in the periphery region of the MCA territory after MCA occlusion was markedly exaggerated in hRN/hANG-Tg mice. Superoxide anion production in the brain and arteries was also increased significantly in hRN/hANG-Tg mice even before MCA occlusion and was further enhanced after MCA occlusion. Treatment with an AT1 receptor blocker, valsartan (3.0 mg/kg per day), for 2 weeks significantly reduced the ischemic brain area and improved the neurological deficit after MCA occlusion in hRN/hANG-Tg mice, similar to those in wild-type, hRN-Tg, and hANG-Tg mice, with restoration of cerebral blood flow in the peripheral region and decreases in superoxide anion production and blood pressure. CONCLUSIONS: These results indicate that activation of the human renin-angiotensin system exaggerates ischemic brain damage mainly through stimulation of the AT1 receptor and marked reduction of cerebral blood flow and enhanced oxidative stress.
Angiotensin inhibition stimulates PPARgamma and the release of visfatin.
Eur J Clin Invest. 2008 Nov; 38(11): 820-826
Storka A, Vojtassakova E, Mueller M, Kapiotis S, Haider DG, Jungbauer A, Wolzt M
Background Angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) exhibit beneficial antidiabetic effects in patients with type 2 diabetes independent of their blood pressure-lowering effects. Some antidiabetic properties of ARB and ACE-I might by exerted by activation of peroxisome proliferator-activated receptor gamma (PPARgamma). However, it is not clear whether this action is drug specific. Materials and methods The binding affinity of telmisartan, valsartan, lisinopril, rosiglitazone and angiotensin II to PPARgamma was assessed in a cell-free assay system. PPARgamma signalling was studied in isolated skeletal muscle cells using Western blot analysis of phosphorylated protein kinase B (pAKT) and phosphorylated insulin like growth factor-1 receptor (pILGF-1R). Further, the ability of the drugs under study to stimulate the release of the adipocytokine visfatin was investigated in isolated human adipocytes, skeletal muscle cells, and umbilical vein endothelial cells (HUVEC). Results The binding affinity to PPARgamma was highest for telmisartan with a half-maximal effective concentration of 463 nM, followed by lisinopril (2.9 microM) and valsartan (6.2 microM). In skeletal muscle cells phosphorylation of ILGF-1R was 2-fold increased after incubation with telmisartan or valsartan and 1.7-fold with lisinopril. pAKT expression was enhanced after incubation with telmisartan, valsartan and with lisinopril. The release of visfatin from adipocytes was 1.6-fold increased after treatment with lisinopril and about 2.0-fold increased with telmisartan and valsartan. Similar results were obtained in skeletal muscle cells and HUVEC. Conclusions Our data confirm agonism of telmisartan, valsartan and lisinopril on PPARgamma. Pharmacokinetic differences may explain different potencies of PPARgamma stimulation by drugs acting on the renin-angiotensin system in clinical settings.
Int J Mol Med. 2008 Dec; 22(6): 703-708
Fujiwara Y, Shiraya S, Miyake T, Yamakawa S, Aoki M, Makino H, Nishimura M, Morishita R
Angiotensin (Ang) II exerts direct effects on the arterial wall to influence atherosclerosis and aneurysm development with the induction of vascular inflammation. Therefore, we examined the hypothesis that the inhibition of Ang II would decrease the expansion of abdominal aortic aneurysm (AAA) in a rat model. We used the Ang II receptor blocker (ARB) valsartan to inhibit the effect of Ang II. Additionally, we employed a dosage of valsartan (1 mg/ kg/day) that does not affect blood pressure, to avoid the effect of blood pressure lowering. Notably, progression of elastase-induced AAA was inhibited in rats treated with valsartan (P
Hypertens Res. 2008 Oct; 31(10): 1835-42
Mizuta Y, Kai H, Mizoguchi M, Osada K, Tahara N, Nakaura H, Kuwahara F, Imaizumi T
Myocardial fibrosis is the major determinant of diastolic property of the left ventricle (LV). Experimental and clinical studies have suggested that angiotensin receptor blockers attenuate myocardial fibrosis in various heart diseases. The integrated backscatter signal (IBS) represents a promising ultrasonic method for assessing the characterization of myocardial tissue: cardiac cycle-dependent variation of the IBS (IBS-CV) is negatively correlated with myocardial collagen deposition in hypertensive hearts. Using non-invasive echocardiographic techniques, we performed a prospective, multi-center trial to examine whether long-term treatment with valsartan would improve myocardial fibrosis and diastolic dysfunction in hypertensives. This study included 43 hypertensive patients who had impaired diastolic function (transmitral Doppler flow early to late filling velocity ratio [E/A ratio] 50%). Twelve-month valsartan treatment reduced blood pressure (BP) and LV mass index. Valsartan significantly increased not only IBS-CV but also E/A ratio without changing LVEF. The effects of valsartan were compared between two subgroups: one with low IBS-CV (IBS-CV 5.08 dB). At baseline, BP, LV mass index, LVEF, and E/A ratio were similar in the two groups. Valsartan significantly increased IBS-CV and E/A ratio in the low IBS-CV group, but not in the high IBS-CV group, despite comparable reductions in BP and LV mass. In conclusion, long-term valsartan treatment attenuated myocardial fibrosis and improved diastolic dysfunction in hypertensives. It is suggested that in the low IBS-CV group, improvement of diastolic dysfunction by valsartan may be caused by attenuation of myocardial fibrosis, and not by regression of LV hypertrophy. (Hypertens Res 2008; 31: 1835-1842).
Clin Ther. 2008 Oct; 30(10): 1782-93
Rump LC, Baranova E, Okopien B, Weisskopf M, Kandra A, Ferber P
Background: Together, high blood pressure (BP) and high cholesterol levels constitute a cumulative risk for coronary heart disease (CHD). Elevations in cholesterol increase BP through upregulation of angiotensin type 1 receptors, with a corresponding increase in cholesterol oxidation due to elevations in BP. Hence, control of low-density lipoprotein cholesterol (LDL-C) and BP through coadministration of an antihypertensive and a statin have potential benefit in the management of CHD. Objectives: This study examined the dose response to simvastatin 20 and 40 mg in reducing LDL-C and the efficacy and tolerability of a high dose of valsartan (320 mg) when administered with simvastatin. Methods: In this multicenter, 12-week, double-blind, double-dummy, parallel-group superiority study, patients with hypertension and hypercholesterolemia were randomized to receive valsartan 160 mg along with simvastatin 20 or 40 mg. At week 6, valsartan was titrated upward to 320 mg in both groups. The primary efficacy variable was the change in LDL-C, calculated using the Friedewald formula or measured directly (depending on triglyceride levels) and analyzed for superiority. Secondary efficacy variables were the change in LDL-C and the proportion of patients achieving LDL-C and BP control. Safety assessments included the occurrence of adverse events (AEs) and serious AEs, and changes in hematology and biochemistry variables, vital signs, and findings on physical examinations. Results: Eight hundred seventy-two patients were randomized to receive double-blind treatment, and the intent-to-treat population included 838 patients. The combination of valsartan 160 mg + simvastatin 40 mg was statistically superior to that of valsartan 160 mg + simvastatin 20 mg in reducing LDL-C at week 6 (least squares mean percent change from baseline: -38.5% vs -33.6%, respectively; P < 0.001); at week 12, the corresponding values were -36.8% in the valsartan 320 mg + simvastatin 40 mg group and -32.7% in the valsartan 320 mg + simvastatin 20 mg group (P = 0.002). Rates of combined LDL-C and BP control at week 6 were 35.1% (146/416) in the valsartan 160 mg + simvastatin 20 mg group and 37.4% (154/412) in the valsartan 160 mg + simvastatin 40 mg group; at week 12, rates of combined control were 50.7% (212/418) in the valsartan 320 mg + simvastatin 20 mg group and 50.0% (206/412) in the valsartan 320 mg + simvastatin 40 mg group. AEs occurred in 24.3% (102/420) of the valsartan 160/320 mg + simvastatin 20 mg group and 22.2% (93/419) of the valsartan 160/320 mg + simvastatin 40 mg group. Conclusions: In these patients with hypertension and hypercholesterolemia, coadministration of valsartan and simvastatin was well tolerated and was associated with significant reductions from baseline in BP and LDL-C. Coadministered with valsartan 160/320 mg in the evening, simvastatin 40 mg had superior LDL-C-lowering efficacy to simvastatin 20 mg. Clinical Trials Identification Number: NCT00254475.
Intern Med. 2008; 47(21): 1851-7
Fogari R, Preti P, Zoppi A, Mugellini A, Corradi L, Lazzari P, Santoro T, Derosa G
OBJECTIVE: The aim of the study was to evaluate the effect of valsartan/amlodipine combination on insulin sensitivity in overweight-obese hypertensive patients. METHODS: After a 4-week placebo period, 58 overweight-obese (BMI >or=25 kg/m(2)) patients, with mild to moderate essential hypertension (DBP >95 and 140 mmHg) were treated with amlodipine 5 mg od or valsartan 160 mg od or amlodipine 5 mg plus valsartan 160 mg od for 8 weeks according to a randomized, open-label, blinded end-point, cross-over study. At the end of the placebo period and each treatment period, blood pressure (BP) and insulin sensitivity (IS) (by euglycemic hyperinsulinemic clamp technique) were evaluated. IS was expressed as the amount of glucose infused during the last 30 min (glucose infusion rate, GIR) in mg/kg/min. RESULTS: Valsartan/amlodipine combination produced a significantly greater decrease in SBP/DBP values (-22.3/16.7 mmHg, p
Ameliorative effect of captopril and valsartan on an animal model of diabetic cardiomyopathy.
Biol Pharm Bull. 2008 Nov; 31(11): 2045-9
Zhang CH, Lu J, Yu XJ, Sun L, Zang WJ
The objective of this study was to clarify the relationship between angiotensin II and the pathogenesis of diabetic cardiomyopathy by observing the effects of related drugs on diabetic cardiomyopathy in rats. Captopril and Valsartan, an automatic biochemical analyzer, and radioimmunoassay technology were used to an experimental rat model of diabetic cardiomyopathy to dynamically measure the levels of creatine kinase-MB, lactate dehydrogenase-1 in the serum, and angiotensin I and II in the plasma, and to observe changes in the myocardial ultrastructure. The content of angiotensin I and II was increased and the renin-angiotensin system was in a hyperfunctional state in experimental rats with myocardial damage. Angiotensin-converting enzyme inhibitors and angiotensin II receptor 1 antagonists improved the myocardial structure and cardiac function. It is concluded that hyperfunction of the renin-angiotensin system is involved in the pathogenesis of diabetic cardiomyopathy, with an increase in angiotensin being a key factor. Preventing the increase in angiotensin II or the action of angiotensin II on its receptor can prevent the occurrence and development of diabetic cardiomyopathy.
Renal Hemodynamics and Renoprotection.
Nephron Clin Pract. 2008 Oct 31; 110(4): c213-c219
Loriga G, Vidili G, Ruggenenti P, Faedda R, Sanna M, Satta AE
Background: Angiotensin II (AII) is the well-known determinant of kidney damage increasing intraglomerular pressure, matrix expansion and fibroblast proliferation. Renin-angiotensin system (RAS) inhibition, limiting the hemodynamic effects of AII, reduces proteinuria and is renoprotective in the long term. Methods: We studied 15 chronic proteinuric patients by Doppler ultrasonography to clarify the intrarenal hemodynamic changes during RAS blockade by Benazepril (10-20 mg/day) alone and combined with Valsartan (80-160 mg/day). We also investigated the correlation between hemodynamic indices, RAS components and antiproteinuric effect. Results: After 1 month of Benazepril proteinuria, resistive index (RI) and pulsatility index (PI) significantly decreased and proteinuria reduction was directly correlated to decrease in RI (r = 0.55, p = 0.03). Contrarily, after 1 month of combined therapy, RI and PI restored to baseline and progressively increased in the following 3 months, while proteinuria decreased. Increase in RI was directly correlated to concomitant increase in plasma renin activity (r = 0.65, p = 0.01) suggesting a direct role of renin in restoring intrarenal resistances. Conclusion: The hemodynamic changes caused by RAS inhibitors partially contribute to the antiproteinuric effect. Other RAS components, such as renin, may contribute to renal vasoconstriction and could be a further determinant of kidney damage besides a promising target for renoprotection.
Hypertens Res. 2008 Aug; 31(8): 1517-24
Konishi Y, Morikawa T, Okada N, Maeda I, Kitabayashi C, Yoshioka K, Okumura M, Nishiyama A, Ueda M, Takai S, Miyazaki M, Imanishi M
Several investigators have reported chymase-positive mast cells in tubulointerstitial damage. However, the significance of the presence of chymase in the pathophysiology of renal diseases is unclear. We investigated relationships among chymase, renal damage, and intra-renal circulation. The participant pool consisted of 52 patients with immunoglobulin A (IgA) nephropathy who underwent renal biopsy. Of these, 18 were examined before and 2 months after the initiation of treatment with prednisolone alone (n=9) or combined with the angiotensin II receptor blocker valsartan (n=9). Biopsied renal specimens were evaluated, and the degree of renal circulation (resistive index; RI) was calculated by measuring flow velocity using Doppler sonography. The number of chymase-positive mast cells as visualized by immunohistochemical staining correlated significantly with both tubulointerstitial damage (rho=0.69, p
Talanta. 2001 Jul 6; 54(6): 1121-33
Cagigal E, González L, Alonso RM, Jiménez RM
A spectrofluorimetric method has been developed for the determination of two angiotensin II receptor antagonists (ARA II): Losartan and Valsartan. A fractional factorial design and a central composite design were used. The key factors considered in the optimization process were pH, temperature and emission slit width. Maximum fluorescent intensity was established as response for each experiment. The response surfaces confirmed the robustness of the method. A clean-up procedure was used for urine samples that consisted of a solid-phase extraction using C8 cartridges. The total analysis time was lower than 30 min. This method proved to be accurate (RE, 8%), precise (intra- and inter-day coefficients of variation were lower than 8% and sensitive enough (LOQ c.a. 0.5 mug ml(-1)) to be applied to the determination of Losartan and Valsartan in urine samples.