Dopamine produced by renal proximal tubules increases sodium excretion via a decrease in renal sodium reabsorption. Dopamine natriuresis is impaired in obese Zucker rats; however, the mechanism is not fully understood. To test the hypothesis that renal expression of one or more of the subtypes is altered in these rats, we measured whole kidney protein levels by immunoblotting of D1-like (D1R and D5R) and D2-like (D2R, D3R, and D4R) dopamine receptors in both male and female obese and lean Zucker rats. In obese males on 1%-NaCl diet, D1R, D2R, D4R, and D5R were decreased, while D3R was increased, relative to lean rats. Under a 4%-NaCl diet, D2R and D3R levels in obese rats were restored to lean levels. 4%-NaCl diet reduced D5R in both body types, relative to 1%-NaCl diet. Female rats had higher expression of D1R and D3R than did male; however the sex difference for D1R was markedly blunted in obese rats. In obese rats, dietary candesartan (angiotensin II type 1 receptor blocker) normalized down-regulated D1R and D2R, but either decreased (D3R), did not affect (D4R), or further down-regulated (D5R) the other subtypes. Candesartan also decreased D4R in lean rats. In summary, reduced renal protein levels of D1R, D2R, D4R, and D5R in obese Zucker rats could induce salt-sensitivity and elevate blood pressure. Increased AT1R activity may be mechanistically involved in the decreased expression of D1R and D2R in obese rats. Finally reduced D1R and D3R in male rats may contribute to sex differences in blood pressure.

BACKGROUND: The mechanisms of uraemia-induced atherosclerosis have not been fully delineated. The aims of this study were (i) to investigate the extent and the phenotype of atherosclerosis, including the activation of local renin-angiotensin system (RAS), in a mouse model of mild uraemia and (ii) to determine the effects of angiotensin II type1 (AT1) receptor blockade on the uraemic atherosclerosis, clarifying the mechanisms of its action. METHODS: Mild uraemia was induced by 5/6 nephrectomy in 8-week-old apo E-deficient mice (apoE-KO). After nephrectomy, the animals received either treatment with candesartan or no treatment for 12-weeks. Sham-operated apoE-KO mice were used as controls. RESULTS: Uraemia led to a two-fold increase in aortic plaque area. This was associated with a significant upregulation of aortic angiotensin-converting enzyme (ACE), AT1 receptor, connective tissue growth factor (CTGF), monocyte chemoattractant protein (MCP)-1 and vascular cell adhesion molecule (VCAM)-1. Candesartan significantly reduced aortic atherosclerosis, prevented the upregulation of the uraemia-induced genes and led to changes predicting greater stability of the plaques, without influencing blood pressure or serum lipids. CONCLUSIONS: This study indicates that uraemia leads to an acceleration of aortic atherosclerosis. The upregulation of aortic RAS and the reduced atherosclerosis following AT1 receptor blocker treatment highlights the pivotal role of the local RAS in the development and acceleration of atherosclerosis in uraemia.

Background: In this subanalysis of the CASE-J, which was conducted to compare the effects of candesartan and amlodipine in Japanese high-risk hypertensive patients, the association of left ventricular hypertrophy (LVH) with renal function is clarified. Methods and Results: Patients were divided into 2 groups: 1,082 patients with LVH and 2,119 patients without LVH. The primary endpoint was the change in the estimated glomerular filtration rate (eGFR). The eGFRs were increased from 63.6 to 65.1 ml . min(-1) . 1.73 m(-2) in patients with LVH and from 63.6 to 68.5 ml . min(-1) . 1.73 m(-2) in those without LVH. The improvement in the eGFR was greater in patients without LVH than in those with LVH (P=0.004). In patients with chronic kidney disease (CKD) patients, the eGFR increased from 52.7 to 60.5 ml . min(-1) . 1.73 m(-2) in patients without LVH, but from 53.1 to 57.2 ml . min(-1) . 1.73 m(-2) in those with LVH (P<0.001, patients without LVH vs patients with LVH). Furthermore, because the eGFR changed from 76.5 to 75.4 ml . min(-1) . 1.73 m(-2) in patients without CKD but with LVH, and from 76.5 to 77.5 ml . min(-1) . 1.73 m(-2) in those without either CKD or LVH, the final eGFR was higher in patients without LVH than in those with LVH (P=0.048). Conclusions: LVH related to the time-course of renal function in Japanese hypertensive patients.

Angiotensin receptor blockers (ARBs) are known to reduce the cardiovascular risk in hypertensive patients. This study was designed to examine the effect of an ARB candesartan on subclinical atherosclerosis assessed by cardio-ankle vascular index (CAVI) in comparison with calcium channel blockers (CCBs) alone in hypertensive patients with metabolic syndrome (MetS). A total of 53 consecutive hypertensive patients with MetS were randomly assigned to the candesartan group, in which candesartan was added on, or the CCBs group, in which CCBs were added on. Clinical and biological parameters were obtained before and after the 12-month treatment period. The primary measure of efficacy was the %change in CAVI. When treated with candesartan, but not CCBs, CAVI significantly decreased from 8.7 to 7.7 by 11%. Blood pressure (BP) significantly decreased with both treatments, but the differences between groups were not significant. The changes in other parameters remained unchanged in both the groups. Analysis of covariance found that both the BP reduction and the therapy difference contributed to the decrease in CAVI, but the BP reduction was not involved in the decrease in CAVI caused by the difference in the therapy. Candesartan may be a better antihypertensive drug than CCBs to improve subclinical atherosclerosis of patients with MetS.

INTRODUCTION:: Previous studies have demonstrated that the urinary excretion of angiotensinogen is significantly increased in ANG II-infused hypertensive rats, which is associated with an augmentation of intrarenal ANG II levels. These findings suggest that urinary angiotensinogen excretion rates provide an index of intrarenal ANG II levels in ANG II-dependent hypertensive states. However, little information is available regarding the urinary excretion of angiotensinogen in ANG II-dependent malignant hypertension. METHODS:: This study was performed to determine if urinary angiotensinogen excretion is increased in Cyp1a1-Ren2 transgenic rats [strain name: TGR(Cyp1aRen2)] with inducible ANG II-dependent malignant hypertension. Adult male Cyp1a1-Ren2 rats (n = 6) were fed a normal diet containing 0.3%; indole-3-carbinol (I3C) for 10 days to induce ANG II-dependent malignant hypertension. RESULTS:: Rats induced with I3C exhibited pronounced increases in systolic blood pressure (208 +/- 7 versus 127 +/- 3 mm Hg; P < 0.001), marked proteinuria (29.4 +/- 3.6 versus 5.9 +/- 0.3 mg/d; P < 0.001) and augmented urinary angiotensinogen excretion (996 +/- 186 versus 241 +/- 31 ng/d; P < 0.01). Chronic administration of the AT1 receptor antagonist, candesartan (25 mg/L in drinking water, n = 6), prevented the I3C-induced increases in systolic blood pressure (125 +/- 5 mm Hg; P < 0.001), proteinuria (7.3 +/- 1.0 mg/d; P < 0.001) and urinary angiotensinogen excretion (488 +/- 51 ng/d, P < 0.01). CONCLUSIONS:: These data demonstrate that the urinary excretion of angiotensinogen is markedly augmented in ANG II-dependent malignant hypertension. Such increased urinary angiotensinogen excretion may contribute to augmented intrarenal ANG II levels and, thereby, to the increased blood pressure in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension.

In hypertension, angiotensin receptor blockers can augment regression of left ventricular (LV) hypertrophy. It is not known whether this also is the case after aortic valve replacement (AVR) for severe aortic stenosis (AS). To test the hypothesis that treatment with candesartan in addition to conventional treatment is able to augment LV and left atrial (LA) reverse remodeling in patients with AS undergoing AVR, we studied 114 patients scheduled for AVR. Patients were randomized to treatment with candesartan 32 mg 1 time/day or conventional therapy immediately after AVR. Patients were followed with echocardiographic evaluations 3, 6, and 12 months after surgery. Primary end point was change in LV mass index. At baseline and during follow-up no differences in systolic, diastolic, and pulse pressures were seen between groups. Baseline LV mass index was 134 +/- 41 g/m(2) with no difference between groups. Mean decrease in LV mass index in the control group was 12 +/- 28 g/m(2) compared to 30 +/- 40 g/m(2) in the candesartan group (p = 0.015) during follow-up. After 12 months LV mass index was significantly lower in the candesartan group (103 +/- 29 vs 119 +/- 31 g/m(2), p = 0.01). In addition, the candesartan group had greater improvement in longitudinal LV systolic function assessed by tissue Doppler S' wave (0.6 +/- 0.1-cm/s increase in control group vs 1.4 +/- 0.1 cm/s in candesartan group, p = 0.01, p for trend = 0.02) and a decrease in LA volume (p for trend = 0.01). Treatment had no effect on diastolic E/e' ratio or B-type natriuretic peptide. In conclusion, angiotensin receptor blockade with candesartan after AVR in patients with AS is associated with augmented reverse LV and LA remodeling compared to conventional management.

The capacity of renin angiotensin system (RAS) inhibitors to delay progression of diabetic nephropathy depends on the time at which therapy is started. A multimodal intervention is required to afford renoprotection in overt diabetic nephropathy. Here we assessed the effects of maximal RAS inhibition by angiotensin converting enzyme (ACE) inhibitor plus angiotensin II type I receptor blocker (ARB) in combination with statin in rats with overt diabetic nephropathy. Uninephrectomized rats made diabetic by streptozotocin were orally treated from 4 (when proteinuria and renal lesions had developed) to 8 months with vehicle, lisinopril plus candesartan, lisinopril plus candesartan plus rosuvastatin or rosuvastatin alone. Systolic blood pressure increased in diabetic rats and was significantly lowered by combined therapies. Dual RAS blockade significantly reduced proteinuria with respect to vehicle. Addition of statin further lowered proteinuria to control levels. Glomerulosclerosis was ameliorated by RAS inhibitors or statin, and regression was achieved by the addition of statin. Loss of podocytes of diabetic rats was limited by ACE inhibitor plus ARB, while normalized by the three drugs. Defective nephrin expression of diabetes was increased by dual RAS blockade or statin, and restored by the triple therapy. Tubular damage, interstitial inflammation, and the expression of the fibrotic markers TGFbeta1 and phosphorylated Smad 2/3 in tubuli were significantly reduced by the triple regimen. These data suggest a strategy to target proteinuria to try to achieve regression of renal disease in diabetic patients who do not fully benefit RAS inhibition alone.

The combined effects of curcumin and candesartan were investigated in brain ischemia induced by middle cerebral artery (MCA) occlusion (MCAO). Male mice were classified into 5 groups. The mice were killed 24 hours after MCAO, and each group was divided into 2 halves. In one half, brain homogenate was collected for antioxidant enzyme activity determination, and in the other half, samples were obtained for red color intensity determination in brain slices. The untreated group exhibited significantly reduced cerebral blood flow, increased lipid peroxide levels and heart rate, decreased superoxide dismutase (SOD) and glutathione-S-transferase (GST) activity, and reduced red color intensity compared with the sham group. Combination treatment with curcumin and candesartan significantly restored SOD and GST activity, thiobarbituric acid reactive substances, heart rate, blood flow, and red color intensity compared with the untreated group. The use of each drug alone significantly restored SOD and blood flow compared with the sham and untreated groups, heart rate decreased with curcumin alone, and red color intensity and nitric oxide level increased with candesartan alone. These results indicate that curcumin synergistically enhances the inhibitory action of candesartan on brain ischemia through suppression of blood flow changes and oxidative stress via antioxidant properties, suggesting beneficial combined effects of curcumin and candesartan on ischemic brain damage.

ABSTRACT: BACKGROUND: Studies focusing on the add-on effects of angiotensin II type 1 receptor blockers (ARBs) other than their antihypertensive effect are receiving attention. However, the effects of prolonged administration of ARBs on lipid metabolism in clinical cases are unclear. Our aims were to survey the changes in plasma lipid profile in patients with hypertension over a one-year period, and to examine the correlations between these values and the time after the start of ARB monotherapy with candesartan. METHODS: We carried out candesartan monotherapy in patients with mild to moderate hypertension and examined the longitudinal changes in plasma lipid profile. Data from 405 patients for triglyceride (TG), 440 for total cholesterol (TC), 313 for high density lipoprotein cholesterol (HDL-C) and 304 for low density lipoprotein cholesterol (LDL-C) were obtained from the electronic medical records (EMRs) in the Clinical Data Warehouse (CDW) of Nihon University School of Medicine (NUSM). The inverse probability of treatment weighting (IPTW) method (calculated from the inverse of the propensity score) was used to balance the covariates and reduce bias in each treatment duration. Linear mixed effects models were used to analyse the relationship between these longitudinal data of blood examinations and covariates of patient sex, age, diagnosis of diabetes mellitus (DM) and duration of candesartan monotherapy. RESULTS: Plasma HDL-C level was associated with sex, duration of treatment, and interaction of sex and treatment duration, but not with age or diagnosis of DM. HDL-C level was significantly decreased during the 6~9 months period (p=0.0218) compared with baseline. TG and TC levels were associated with sex, but not with age, diagnosis of DM or treatment duration. LDL-C level was not associated with any covariate. Analysis of the subjects divided by sex revealed a decrease in HDL-C in female subjects (during the 6~9 months period: p=0.0054), but not in male subjects. CONCLUSIONS: Our study revealed that administration of candesartan slightly decreased HDL-C in female subjects. However, TG, TC and LDL-C levels were not influenced by candesartan monotherapy. Candesartan may be safely used for patients with hypertension with respect to lipid metabolism, because the effect of candesartan on lipids may be small.

The ACCESS (Acute Candesartan Cilexetil Therapy in Stroke Survivors) study found that administration of candesartan in the acute phase of stroke confers a long-term benefit in patients who have sustained acute ischemic stroke. This treatment did not significantly reduce blood pressure (BP) during the acute phase, however. We assessed the short-term safety of reducing BP with renin-angiotensin system blockade in hypertensive patients who sustained acute ischemic stroke. Our randomized study compared the effects of 14 days of oral candesartan (4mg/day), perindopril (4mg/day), or conventional therapy (topical nitrate only when systolic BP (SBP) was>/=220mm Hg or diastolic BP (DBP) was>/=120mm Hg) administered to hypertensive patients within 72hours of the onset of minor ischemic stroke. We assessed neurologic symptoms using the National Institutes of Health Stroke Scale and the modified Rankin Scale within 72hours of stroke onset before and after drug therapy. A total of 40 patients completed the protocol. Therapy with candesartan and perindopril reduced SBP/DBP values by 23/11mm Hg (SBP, P < .01; DBP, P=.07) and 14/0mm Hg (SBP, P=.07), respectively, compared with conventional treatment. Neurologic symptoms worsened in 2 patients who received perindopril, which has no statistical significance, despite the BP reduction in patients given candesartan or perindopril. Our findings indicate that low doses of candesartan or perindopril safely reduce SBP in hypertensive patients with acute ischemic stroke.

- Migraine patients who experience an average of 2 or more attacks per month are eligible for preventive treatment as well as treatment for acute attacks. The decision to offer preventative treatment is also made on the basis of the average attack duration, severity of the attacks, and response to attack treatment. - Prior to initiating preventive treatment, the average attack frequency per month should be assessed, preferably by means of a headache diary over a number of months, as attack frequency is extremely variable.- None of the currently available preventive drugs, such as beta-blockers, sodium valproate, topiramate and candesartan, were developed specifically for treating migraine, but were all originally intended for other indications. - 50% of the migraine patients receiving preventive treatment can expect a 50% reduction in attacks, and the remaining attacks often seem to be less severe. The effects of the drugs are often unpredictable per individual, and side-effects frequently lead to early discontinuation of treatment.- Drugs usually prescribed for cardiovascular disorders are often used. In the case of a disorder such as migraine with a high burden of disability, patients with cardiovascular or pulmonary comorbidity should receive medication that is optimally adjusted for both indications.

Asymmetrical dimethylarginine inhibits nitric oxide synthase, cationic amino acid transport, and endothelial function. Patients with cardiovascular risk factors often have endothelial dysfunction associated with increased plasma asymmetrical dimethylarginine and markers of reactive oxygen species. We tested the hypothesis that reactive oxygen species, generated by nicotinamide adenine dinucleotide phosphate oxidase, enhance cellular asymmetrical dimethylarginine. Incubation of rat preglomerular vascular smooth muscle cells with angiotensin II doubled the activity of nicotinamide adenine dinucleotide phosphate oxidase but decreased the activities of dimethylarginine dimethylaminohydrolase by 35% and of cationic amino acid transport by 20% and doubled cellular (but not medium) asymmetrical dimethylarginine concentrations (P<0.01). This was blocked by tempol or candesartan. Cells stably transfected with p22(phox) had a 50% decreased protein expression and activity of dimethylarginine dimethylaminohydrolase despite increased promoter activity and mRNA. The decreased DDAH protein expression and the increased asymmetrical dimethylarginine concentration in p22(phox)-transfected cells were prevented by proteosomal inhibition. These cells had enhanced protein arginine methylation, a 2-fold increased expression of protein arginine methyltransferase-3 (P<0.05) and a 30% reduction in cationic amino acid transport activity (P<0.05). Asymmetrical dimethylarginine was increased from 6+/-1 to 16+/-3 mumol/L (P<0.005) in p22(phox)-transfected cells. Thus, angiotensin II increased cellular asymmetrical dimethylarginine via type 1 receptors and reactive oxygen species. Nicotinamide adenine dinucleotide phosphate oxidase increased cellular asymmetrical dimethylarginine by increasing enzymes that generate it, enhancing the degradation of enzymes that metabolize it, and reducing its cellular transport. This could underlie increases in cellular asymmetrical dimethylarginine during oxidative stress.

Elevated glucose concentration increases oxidation and Advanced Glycation End product (AGE) formation. The binding of circulatory AGEs or AGEs included in erythrocyte membrane to the receptor for AGEs (RAGE) generates in endothelial cells an oxidative stress and enhances the expression of inflammatory molecules. Engagement of RAGE by AGEs and subsequent signaling plays an important role in the development of diabetic complications. Soluble RAGE isoforms (sRAGE) neutralize the ligand-mediated damage by acting as a decoy. If the expression of RAGE is upregulated during the pathogenesis of inflammatory diseases, sRAGE mostly found decreased when complications ensue. By modulating RAGE isoform expression, it could be possible to reduce the incidence of complications. This review focused on the capability of Angiotensin Receptor Blockers (ARBs), which are used to treat patients with hypertension and/or diabetes, to modulate RAGE isoform expression because some data reported the interference with RAGE downstream. In this regard, three ARBs - irbesartan, telmisartan, candesartan cilexetil - were tested and provided evidence for their ability to inhibit in human endothelial cells the expression of membrane-bound and soluble RAGE isoforms induced by the inflammatory factor Tumor Necrosis Factor-alpha (TNF-alpha), demonstrating the potential benefits of these molecules in RAGE-oriented therapies. Modulating RAGE isoforms expression by correcting endothelial dysfunction is achievable by drugs already used for hypertension or diabetes treatment such as ARBs.

Abstract Objective: To compare blood pressure (BP) goal achievement associated with the use of valsartan-based single pill combinations (SPCs) vs. angiotensin II receptor blocker (ARB)-based free combinations (FCs) among adult hypertension patients. Research design and methods: Data were collected from physician-administered chart review of adult hypertension patients in the South Central region. All patients had uncontrolled BP before initiating one of the index therapies (SPCs: valsartan/amlodipine or valsartan/hydrochlorothiazide [HCTZ], FCs: ARB + calcium channel blocker [CCB] or ARB + HCTZ) between 07/2008 and 06/2009. Up to three BP measures were collected starting from 45 days after the therapy initiation. BP goal was <130/80 mmHg for patients with diabetes, chronic renal disease or coronary heart disease; or <140/90 mmHg for patients without these comorbidities. The Kaplan-Meier method with log-rank test was used to compare rates of BP goal achievement associated with valsartan-based SPCs vs. ARB-based FCs over time. Cox proportional hazard models were used to estimate the likelihood of BP goal achievement associated with SPCs vs. FCs, controlling for demographics, baseline BP, hypertension history, comorbidities, prior and concurrent use of anti-hypertensive medications, and physician specialty. Results: The study included 812 patients: 414 on valsartan-based SPCs (209 on valsartan/amlodipine and 205 on valsartan/HCTZ) and 398 on ARB-based FCs (200 on ARB + CCB and 198 on ARB + HCTZ). The ARBs in the FC group included valsartan, losartan, olmesartan, telmisartan, irbesartan and candesartan. In the ARB FC group, the most commonly used ARB and CCB were valsartan (29.1%) and amlodipine (81.5%), respectively. During the observation period (81 days for valsartan SPC patients and 90 days for ARB FC patients), 65.9% of valsartan SPC patients and 55.8% of the ARB FC patients achieved BP goal. Over time, the rates of BP goal achievement were consistently higher among valsartan SPC vs. ARB FC patients (p = 0.01): 31.1% vs. 28.9% and 69.1% vs. 59.2% at month 3 and 6 after therapy initiation, respectively. Cox regression confirmed that valsartan SPC patients were more likely to achieve BP goal (HR = 1.22; p = 0.05). A similar trend was observed in the subgroup analyses comparing SPC of valsartan/amlodipine vs. FCs of ARB + CCB and SPC of valsartan/HCTZ vs. FCs of ARB + HCTZ. Limitations: Non-randomization of treatments, limited generalizability, and no records of BP measures within 45 days. Conclusions: Patients using valsartan-based SPCs were significantly more likely to achieve BP goal than those treated with ARB-based FCs in the real-world clinical practice in the South Central region. The significance was achieved at two-sided alpha = 0.05.

A positive association between renin angiotensin system, especially AT1 receptor and oxidative stress in the pathogenesis of hypertension and cardiovascular/renal diseases has been suggested. However, the role of oxidative stress, especially superoxide radicals in renal sodium handling in response to AT1 and AT2 receptors is not known. Therefore, the present study was designed to investigate the role of NAD(P)H oxidase (NOX), a major superoxide radical producing enzyme, in AT1 and AT2 receptor function on natriuresis/diuresis in SD rats. The rats under anesthesia were intravenously infused with NOX inhibitor apocynin (3.5 mug/kg/min), the AT1 receptor antagonist candesartan (100 mug/kg; bolus) and the AT2 receptor agonist CGP- 42112A (1 mug/kg/min) alone and in combinations. Candesartan alone significantly increased urinary flow (UF, microl/30 min) by 53 and urinary Na-excretion (UNaV, micromole/min) by 0.4 over basal. Pre-infusion of apocynin had no effect on the net increase in UF or UNaV in response to candesartan. On the other hand, apocynin pre-infusion caused profound increases in CGP-42112A-induced UF by 72, UNaV by 1.14 and FENa% by 7.8. Apocynin and CGP-42112A alone did not cause significant increase in UF or UNaV over the basal. CGP-42112A infusion in the presence of apocynin increased urinary nitrite/nitrates and cGMP over basal. The infusion of candesartan, apocynin and CGP-42112A alone or in combinations had no effect on the blood pressure or the GFR, suggesting tubular effects on natriuresis/diuresis. The data suggest that NOX may have an antagonistic role in AT2 receptor-mediated natriuresis/diuresis possibly via neutralizing NO and thereby influence fluid-Na homeostasis.

Angiotensin II receptor blockers (ARBs) have been shown to decrease insulin resistance in obese diabetic animal models and reduce the risk of new-onset diabetes in hypertensive patients. In the present study, we studied whether candesartan, an ARB, can exert a direct effect against fatty acid-induced oxidative stress in pancreatic beta-cells. The effect of candesartan on lipotoxicity was evaluated using mouse insulin-secreting clonal cell, MIN6 and isolated mouse pancreatic islets. Intracellular insulin and triglyceride content, uncoupling protein-2 (UCP-2) mRNA expression, reactive oxygen species, protein kinase C (PKC) and NAD(P)H oxidase activity were examined. Candesartan recovered decreased insulin content in MIN6 exposed to 25mM glucose with 0.5mM palmitate (P<0.01). Candesartan tended to decrease intracellular triglyceride accumulation in cells exposed to 25mM glucose with 0.5mM palmitate. Palmitate-induced up-regulation of UCP-2 mRNA levels was suppressed by candesartan in a dose-dependent manner. Candesartan decreased palmitate-induced reactive oxygen species accumulation in MIN6 cells by 23% and in mouse islets by 59%. Candesartan also decreased palmitate-induced PKC activity by 21% and NAD(P)H oxidase activity by 37% in MIN6 cells. These findings indicated that candesartan attenuated fatty acid-induced oxidative stress and NAD(P)H oxidase activity in pancreatic beta-cells.

Both mechanical and humoral triggers have been put forward to explain the hypertrophic response of the challenged cardiomyocyte. The present aim was to investigate whether cyclic equibiaxial stretch is a direct stimulus for isolated adult rabbit cardiomyocytes to develop hypertrophy and to explore the potential involvement of the autocrine/paracrine factors Angiotensin II (AngII), Transforming Growth Factor-beta1 (TGFbeta1) and Insulin-like Growth Factor-I (IGF-I) in this process. Isolated cardiomyocytes were exposed to 10% cyclic equibiaxial stretch (1 Hz) for up to 48h, or treated with AngII (100 nM), TGFbeta1 (5 ng/ml), IGF-I (100 ng/ml), AngII-type 1 receptor (AT-1) blockers, or conditioned medium of stretched fibroblasts. Cyclic stretch significantly increased cell surface area (+3.1%), protein synthesis (+21%) and BNP mRNA expression (6-fold) in cardiomyocytes. TGFbeta1 expression was increased (+42%) transiently at 4h, while cardiomyocyte IGF-I expression was not detectable under all experimental conditions. AT-1 blockers candesartan and irbesartan (100 nM) did not prevent the stretch-induced hypertrophic response. Direct exposure to AngII, TGFbeta1 or IGF-I did not enhance cardiomyocyte BNP expression. In cardiac fibroblasts, stretch elicited a significant ~2-fold increase in TGFbeta1 and IGF-I expression. Conditioned medium of stretched fibroblasts increased BNP expression in cardiomyocytes (~2-fold; P=0.07). This study clearly indicates that cyclic stretch is a strong, direct trigger to induce hypertrophy in fully differentiated rabbit cardiomyocytes. The present findings do not support the notion that stretch-mediated hypertrophy of adult rabbit cardiomyocytes involves autocrine/paracrine actions of AngII, TGFbeta1 or IGF-I.

We evaluated celiprolol-induced vasodilatation in aortas taken from 12-week-old spontaneously hypertensive rats (SHR) and the effect of AT(1) angiotensin II receptor antagonism on the vasodilatory action of celiprolol in Wistar Kyoto (WKY) rats and SHR. In WKY rats, the celiprolol-induced relaxation was greatly decreased in denuded aortas, and completely abolished in intact aortas by N(omega)-nitro-l-arginine methyl ester (l-NAME, 100muM). In SHR, celiprolol-induced relaxation was reduced compared to WKY rats (E(max) (value obtained for the highest concentration, 300muM)=39.1+/-3.78%, n=21 vs. 80.4+/-3% in WKY rats, n=10; P<0.0001). Endothelium removal or pre-treatment with l-NAME did not alter celiprolol-induced relaxation in SHR. In both strains, relaxation to celiprolol was decreased in the presence of nadolol (a beta(1)/beta(2)-adrenoceptor antagonist, 10muM). N-[[3-[(2S)-2-hydroxy-3-[[2-[4-[(phenylsulfonyl)amino] phenyl]ethyl]amino] propoxy]phenyl]methyl]-acetamide (L748337, a beta(3)-adrenoceptor antagonist, 7muM) had no effect. A 12-day treatment with candesartan cilexetil (an AT(1) receptor antagonist, 0.37 or 1mg/kg/day) reduced systolic blood pressure in both strains, but only improved relaxation to celiprolol in SHR, and only at the highest dose (E(max)=64.2+/-3.9%, n=10, P<0.0001 vs. SHR control). In both strains, local aortic AT(1) receptor antagonism with candesartan CV11974 (100muM) had no effect. The endothelial beta(1)/beta(2) relaxation induced by celiprolol was therefore impaired in SHR aortas and AT(1) receptor antagonism improved the response to celiprolol, in conjunction with a reduction in blood pressure. This work highlights the need to analyse the potential benefit of a combination of celiprolol/AT(1) receptor antagonist in the treatment of hypertension.