Pressure overload diseases, such as valvular stenosis and systemic hypertension, manifest morphologically in patients as cardiac concentric hypertrophy. Prevention of cardiac remodeling due to increased pressure overload is important to reduce morbidity and mortality. Epigallocatechin-3 gallate (EGCG) is a major bioactive polyphenol present in green tea which has been found to be a nitric oxide-mediated vasorelaxant and to be cardioprotective in myocardial ischemia-reperfusion injury. Therefore, we investigated whether EGCG supplementation could reduce in vivo pressure overloadmediated cardiac hypertrophy. Cardiac hypertrophy was induced by suprarenal transverse abdominal aortic constriction (AC) in rats. Three weeks after AC surgery, heart to body weight ratio increased in the AC group by 34% compared to the sham group. EGCG administration suppressed the load-induced increase in heart weight by 69%. Attenuation of cardiac hypertrophy by EGCG was associated with attenuation of the increase in myocyte cell size and fibrosis induced by aortic constriction. Despite abolition of hypertrophy by EGCG, transstenotic pressure gradients did not change. Echocardiogram revealed that increased left ventricular systolic dimensions and deteriorated systolic function were relieved by EGCG. These results suggest that EGCG prevents the development of left ventricular concentric hypertrophy by pressure overload and may be a useful therapeutic modality to prevent cardiac remodeling in patients with pressure overload myocardial diseases.
Animals ; Blood Pressure/drug effects ; Cardiomegaly/pathology/*prevention & control ; Catechin/*analogs & derivatives/pharmacology ; Echocardiography ; Heart Rate/drug effects ; Histocytochemistry ; Male ; Organ Size/drug effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo explore the effect of atorvastatin on cardiac hypertrophy and to determine the potential mechanism involved.

METHODSAn in vitro cardiomyocyte hypertrophy from neonatal rats was induced with angiotensin II (Ang II) stimulation. Before Ang II stimulation, the cultured rat cardiac myocytes were pretreated with atorvastatin at different concentrations (0.1, 1, and 10 μmol/L). The following parameters were evaluated: the myocyte surface area, 3H-leucine incorporation into myocytes, mRNA expressions of atrial natriuretic peptide, brain natriuretic peptide, matrix metalloproteinase 9, matrix metalloproteinase 2, and interleukin-1β, mRNA and protein expressions of the δ/β peroxisome proliferator-activated receptor (PPAR) subtypes.

RESULTSIt was shown that atorvastatin could ameliorate Ang II-induced neonatal cardiomyocyte hypertrophy in the area of cardiomyocytes, 3H-leucine incorporation, and the expression of atrial natriuretic peptide and brain natriuretic peptide markedly. Meanwhile, atorvastatin also inhibited the augmented mRNA level of several cytokines in hypertrophic myocytes. Furthermore, the down-regulated expression of PPAR- δ/β at both the mRNA and protein levels in hypertrophic myocytes could be significantly reversed by atorvastatin treatment.

CONCLUSIONSAtorvastatin could improve Ang II-induced cardiac hypertrophy and inhibit the expression of cytokines. Such effect might be partly achieved through activation of the PPAR-δ/β pathway.

Angiotensin II ; pharmacology ; Animals ; Atorvastatin Calcium ; pharmacology ; therapeutic use ; Cardiomegaly ; metabolism ; pathology ; prevention & control ; Cells, Cultured ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; pharmacology ; PPAR delta ; genetics ; PPAR-beta ; genetics ; Rats ; Rats, Wistar

OBJECTIVETo study the effect of Sanhuang Jiangtang recipe (SJR) on renin-angiotensin system in local myocardium in diabetic rats.

METHODSRats were made into diabetes model by intraperitoneally administering of streptozocin, and medicated through gastrogavage with SJR (50 g/kg), gliclazide (20 mg/kg), captopril (15 mg/kg) and nitrendipine (30 mg/kg) respectively, for successive 8 weeks, started from 2 weeks after modeling. Levels of fasting blood sugar (FBS), serum insulin (Ins), heart/body weight ratio (H/BW), myocardial angiotensin II (Ang II), angiotensin converting enzyme (ACE) and aldosterone (ALD) were determined. And the mRNA expression of type I angiotensin receptor (AT1R) in myocardium were detected by RT-PCR assay.

RESULTSAs compared with those in the normal rats, levels of FBS, H/BW, Ang II, ACE, ALD and AT1R mRNA expression were higher (all P < 0.05) and level of serum Ins was lower (P < 0.01) in the model rats. SJR, gliclazide, captopril and nitrendipine could slightly reduce the blood sugar level in model rats, but with no increase of serum Ins. All the four drugs could reduce H/BW, Ang II, ACE and AT1R mRNA expression. SJR and captopril could also decrease the ALD content in myocardium.

CONCLUSIONCardiac hypertrophy has been induced in 10 weeks after diabetic modeling. Activation of local myocardial RAS is related to the genesis of diabetic cardiomyopathy. SJR, gliclazide, captopril and nitrendipine could antagonize the genesis of diabetic cardiomyopathy, the mechanism is related to the inhibition of RAS activation in local myocardium.

Animals ; Cardiomegaly ; etiology ; prevention & control ; Diabetes Mellitus, Experimental ; complications ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Hypoglycemic Agents ; pharmacology ; therapeutic use ; Male ; Myocardium ; metabolism ; pathology ; Rats ; Rats, Sprague-Dawley ; Renin-Angiotensin System ; drug effects

BACKGROUNDBradykinin (BK) acts mainly on two receptor subtypes: B(1) and B(2), and activation of B(2) receptor mediates the most well-known cardioprotective effects of angiotensin converting enzyme inhibitors (ACEi), however, the role that B(1) receptor plays in ACEi has not been fully defined. We examined the role of B(1) receptor in the inhibitory effect of ACE inhibitor captopril on rat cardiomyocyte hypertrophy and cardiac fibroblast proliferation induced by angiotensin II (Ang II) and explored its possible mechanism.

METHODSNeonatal cardiomyocytes and cardiac fibroblasts (CFs) were randomly treated with Ang II, captopril, B(2) receptor antagonist (HOE-140) and B(1) receptor antagonist (des-Arg(10), Leu(9)-kallidin) alone or in combination. Flow cytometry was used to evaluate cell cycle, size and protein content. Nitric oxide (NO) and intracellular cyclic guanosine monophosphate (cGMP) level were measured by colorimetry and radioimmunoassay.

RESULTSAfter the CFs and cardiomyocytes were incubated with 0.1 micromol/L Ang II for 48 hours, the percentage of CFs in the S stage, cardiomyocytes size and protein content significantly increased (both P < 0.01 vs control), and these increases were inhibited by 10 micromol/L captopril. However, NO and cGMP levels were significantly higher than that with Ang II alone (both P < 0.01). 1 micromol/L HOE-140 or 0.1 micromol/L des-Arg(10), Leu(9)-kallidin attenuated the effects of captopril, which was blunted further by blockade of both B(1) and B(2) receptors.

CONCLUSIONSActing via B(2) receptor, BK contributes to the antihypertrophic and antiproliferative effects of captopril on cardiomyocytes and CFs. In the absence of B(2) receptor, B(1) receptor may act a compensatory mechanism for the B(2) receptor and contribute to the inhibition of cardiomyocyte hypertrophy and CFs proliferation by captopril. NO and cGMP play an important role in the effect of B(1) receptor.

Angiotensin-Converting Enzyme Inhibitors ; pharmacology ; Animals ; Animals, Newborn ; Captopril ; pharmacology ; Cardiomegaly ; prevention & control ; Cell Proliferation ; drug effects ; Cell Size ; drug effects ; Cyclic GMP ; analysis ; DNA ; biosynthesis ; Fibroblasts ; drug effects ; physiology ; Myocytes, Cardiac ; drug effects ; pathology ; Nitric Oxide ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptor, Bradykinin B1 ; physiology

AIMTo investigate the effects of pioglitazone on cardiac hypertrophy in vitro and in vivo.

METHODSAngiotensin II was used to establish hypertrophy of cardiac myocytes and pioglitazone was applied to these myocytes in various dosages in vitro. ANP and BNP mRNA expression was evaluated by RT-PCR, and the rate of protein synthesis in CM by 3H-leucine incorporation in cardiac myocytes. Left ventricular hypertrophy was induced by incomplete ligation of abdominal aorta of rats and pioglitazone (20 mg x kg(-1). day(-1)) was administrated one week prior to the operation until 4 weeks after the operation. Cytokines mRNA expression in left ventricle was measured by RT-PCR, left ventricular wall thickness and myocyte diameter were determined by pathological method.

RESULTSPioglitazone inhibited ANP and BNP mRNA expression and 3H-leucine incorporation in neonatal rat cardiac myocytes induced by angiotensin II in a dose-dependent manner in vitro. Furthermore, pioglitazone reduced the mRNA expression of proinflammatory cytokines, including interleukin-1 beta and cardiotrophin-1, and inhibited the pressure overload-induced increase in the ratio of heart weight to body weight, left ventricular wall thickness and myocyte diameter of rats in vivo.

CONCLUSIONPioglitazone inhibits cardiac hypertrophy of rats in vitro and in vivo, and may play a role in prevention and treatment of cardiovascular diseases characterized by cardiac hypertrophy in future.

Animals ; Atrial Natriuretic Factor ; metabolism ; Cardiomegaly ; metabolism ; pathology ; prevention & control ; Cell Line ; Cytokines ; metabolism ; Disease Models, Animal ; Interleukin-1beta ; metabolism ; Male ; Myocytes, Cardiac ; drug effects ; metabolism ; Natriuretic Peptide, Brain ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Thiazolidinediones ; pharmacology ; therapeutic use

OBJECTIVETo demonstrate the inhibitory effect of kappa-opioid receptor activation by U50488H on hypertrophy induced by NE in cultured neonatal rat cardiac myocytes and compare its effect with that of prazosin and propranolol.

METHODSThe cellular proliferation was determined with crystal violet staining. The protein content was assayed with Lowry's method. The cardiomyocytes volumes were measured by computer photograph analysis system. The protein synthesis was assayed with [3H]-lencine incorporation method.

RESULTS(1) NE significantly induced the increase of protein content, [3H]-leucine incorporation and cell size without a concomitant increase in cell number in low serum medium. OThese responses were partially suppressed by prazosin or propranolol alone and completely abolished by both in combination. U50488H significantly inhibited the NE-induced increase of protein content, [3H]-leucine incorporation and cell size. The inhibitory effects of U50488H on NE-induced cardiac hypertrophy were greater than either prazosin or propranolol, but comparable to combination of both.

CONCLUSIONNE, acting via both alpha1- and beta-adrenergic pathway, stimulates myocyte hypertrophy. Stimulating kappa-opioid receptor significantly inhibits NE-induced cardiac hypertrophy, which may be related with alpha1- and beta1-adrenergic pathway.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Adrenergic alpha-1 Receptor Antagonists ; pharmacology ; Adrenergic beta-Antagonists ; pharmacology ; Animals ; Animals, Newborn ; Cardiomegaly ; chemically induced ; pathology ; prevention & control ; Cell Enlargement ; drug effects ; Cells, Cultured ; Female ; Male ; Myocytes, Cardiac ; cytology ; Norepinephrine ; Prazosin ; pharmacology ; Propranolol ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; agonists