Cardiac hypertrophy is a common pathological process of various cardiovascular diseases and eventually develops into heart failure. This paper was aimed to study the different pathological characteristics exhibited by different mouse strains after hypertrophy stimulation. Two mouse strains, A/J and FVB/nJ, were treated with isoproterenol (ISO) by osmotic pump to induce cardiac hypertrophy. Echocardiography was performed to monitor heart morphology and function. Mitochondria were isolated from hearts in each group, and oxidative phosphorylation function was assayed in vitro. The results showed that both strains showed a compensatory enhancement of heart contractile function after 1-week ISO treatment. The A/J mice, but not the FVB/nJ mice, developed significant cardiac hypertrophy after 3-week ISO treatment as evidenced by increases in left ventricular posterior wall thickness, heart weight/body weight ratio, cross sectional area of cardiomyocytes and cardiac hypertrophic markers. Interestingly, the heart from A/J mice contained higher mitochondrial DNA copy number compared with that from FVB/nJ mice. Functionally, the mitochondria from A/J mice displayed faster O
Animals ; Cardiomegaly/chemically induced* ; Heart Failure ; Isoproterenol/toxicity* ; Mice ; Mitochondria ; Myocytes, Cardiac/metabolism*

To explore the changes in adrenomedullin (ADM) and receptor activity-modifying protein 2 (RAMP2) mRNA in myocardium and vessels in hypertension, a hypertensive rat model was prepared by administering L-NNA. Contents of ADM in plasma, myocardium and vessels were measured by radioimmunoassay (RIA). The levels of pro-ADM mRNA of myocardium and vessels were determined by competitive quantitative RT-PCR. The results showed that L-NNA induced hypertension and cardiomegaly. The ratio of heart to body weight increased by 35.5% (P<0.01). In hypertensive rats the ir-ADM in plasma, myocardium and vessels was increased by 80%, 72% and 57% (P<0.01), respectively compared with the control. The amounts of ADM mRNA in myocardium and vessels were increased by 50% and 109.2% (P<0.05), respectively, and the amounts of RAMP2 mRNA was increased by 132% and 87% (P<0.01), respectively, compared with control. The levels of ADM in myocardium and vessels were positively correlated with RAMP2 mRNA, the correlation coefficients were 0.741 and 0.885 (P<0.01), respectively. The results obtained indicate that in hypertensive rats, ADM is elevated in plasma, myocardium and ves-myocardium and vessel, and ADM and RAMP2 mRNA are up-regulated in myocardium and vessel. The ADM/RAMP2 system may play an important role in the pathogenesis of hypertension.
Adrenomedullin ; metabolism ; Animals ; Cardiomegaly ; chemically induced ; metabolism ; Hypertension ; chemically induced ; metabolism ; Myocardium ; metabolism ; Nitroarginine ; pharmacology ; RNA, Messenger ; Rats ; Receptor Activity-Modifying Protein 2 ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Up-Regulation

AIMTo study the effect of diabetes-like environment on the cardiac hypertrophy, cultured cardiomyocytes were used to study the effect of high insulin and high glucose on norepinephrine (NE)-induced cardiac hypertrophy.

METHODSUsing cultured myocardial cells as a model, the cellular hypertrophy was observed. The contracting frequency was counted by the inverted microscope, 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] leucine intake method.

RESULTSThe total cellular protein content, cellular volumes, cellular protein synthesis showed an increase in high insulin group and high glucose group compared with control group. High insulin and high glucose and NE group showed a further increase compared with high glucose and NE group.

CONCLUSIONThe high insulin itself induces hypertrophy of the cultured myocardial cells slightly. Meanwhile, imitating diabetes-like environment with high insulin and high glucose and NE can further accelerate hypertrophy of the cultured myocardial cells.

Animals ; Animals, Newborn ; Cardiomegaly ; chemically induced ; metabolism ; Cells, Cultured ; Glucose ; metabolism ; Insulin ; pharmacology ; Myocytes, Cardiac ; drug effects ; metabolism ; Norepinephrine ; adverse effects ; Rats ; Rats, Sprague-Dawley

BACKGROUNDAngiotensin II (Ang II) is a major contributor to the development of heart failure. However, the molecular and cellular mechanisms that underlie this process remain elusive. Inadequate angiogenesis in the myocardium leads to a transition from cardiac hypertrophy to dysfunction, and our previous study showed that Ang II significantly impaired the angiogenesis response. The current study was designed to examine the role of Jagged1-Notch signaling in the effect of Ang II during impaired angiogenesis and cardiac hypertrophy.

METHODSAng II was subcutaneously infused into 8-week-old male C57BL/6 mice at a dose of 200 ng·kg-1·min-1 for 2 weeks using Alzet micro-osmotic pumps. N-[N-(3, 5-difluorophenacetyl)-L-alanyl]-S-phenylglycine tert-butyl ester (DAPT), a γ-secretase inhibitor, was injected subcutaneously during Ang II infusion at a dose of 10.0 mg·kg-1·d-1. Forty mice were divided into four groups (n = 10 per group): control group; Ang II group, treated with Ang II; DAPT group, treated with DAPT; and Ang II + DAPT group, treated with both Ang II and DAPT. At the end of experiments, myocardial (left ventricle [LV]) tissue from each experimental group was evaluated using immunohistochemistry, Western blotting, and real-time polymerase chain reaction. Data were analyzed using one-way analysis of variance test followed by the least significant difference method or independent samples t-test.

RESULTSAng II treatment significantly induced cardiac hypertrophy and impaired the angiogenesis response compared to controls, as shown by hematoxylin and eosin (HE) staining and immunohistochemistry for CD31, a vascular marker (P < 0.05 for both). Meanwhile, Jagged1 protein was significantly increased, but gene expression for both Jag1 and Hey1 was decreased in the LV following Ang II treatment, compared to that in controls (relative ratio for Jag1 gene: 0.45 ± 0.13 vs. 0.84 ± 0.15; relative ratio for Hey1 gene: 0.51 ± 0.08 vs. 0.91 ± 0.09; P < 0.05). All these cellular and molecular effects induced by Ang II in the hearts of mice were reduced by DAPT treatment. Interestingly, Ang II stimulated Hey1, a known Notch target, but did not affect the expression of Hey2, another Notch target gene.

CONCLUSIONSA Jagged1-Hey1 signal might mediate the impairment of angiogenesis induced by Ang II during cardiac hypertrophy.

Animals ; Cardiomegaly ; chemically induced ; metabolism ; Cell Cycle Proteins ; metabolism ; Immunohistochemistry ; Jagged-1 Protein ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Myocardium ; metabolism ; Neovascularization, Physiologic ; drug effects ; Signal Transduction ; drug effects

Cardiotrophin-1 (CT-1) activates a distinct form of cardiac muscle cell hypertrophy in which the sarcomeric units are assembled in series. The aim of the study was to determine the expression pattern of sarcomeric contractile protein α-actin, specialized cytoskeletal protein α-actinin and mitochondrial uncoupling protein-2 (UCP2) in myocardial remodeling induced by chronic exposure to CT-1. Kunming mice were intraperitoneally injected with carboxy-terminal polypeptide (CP) of CT-1 (CT-1-CP, 500 μg·kg(-1)· day(-1)) for 1, 2, 3 and 4 week (s), respectively (4 groups obtained according to the injection time, n=10 each, with 5 males and 5 females in each group). Those injected with physiological saline for 4 weeks served as controls (n=10, with 5 males and 5 females). The heart tissues of mice were harvested at 1, 2, 3 or 4 week (s). Immunohistochemistry (IHC) and Western blotting (WB) were used to detect the distribution and expression of sarcomeric α-actin, α-actinin and mitochondrial UCP2 in myocardial tissues. IHC showed that α-actin was mainly distributed around the nuclei of cardiomyocytes, α-actinin concentrated around the striae and UCP2 scattered rather evenly in the plasma. The expression of α-actin was slightly greater than that of α-actinin and UCP2 in the control group (IHC: χ(2)=6.125; WB: F=0.249, P>0.05) and it gradually decreased after exposure to CT-1-CP. There was no significant difference in the expression of α-actin between the control group and the CT-1-CP-treated groups (χ (2)=7.386, P>0.05). But Western blotting revealed significant difference in the expression of α-actin between the control group and the 4-week CT-1-CP-treated group (F=2.912; q=4.203, P<0.05). Moreover, it was found that the expression of α-actinin increased stepwise with the exposure time in CT-1-CP-treated groups and differed significantly between CT-1-CP-treated groups and the control group (ICH: χ (2)=21.977; WB: F=50.388; P<0.01). The expression of UCP2 was initially increased (WB: control group vs. 1- or 2-week group, q values: 5.603 and 9.995, respectively, P<0.01) and then decreased (WB: control group vs. 3-week group, q=4.742, P<0.01; control group vs. 4-week group, q=0.558, P>0.05). It was suggested that long-term exposure to CT-1-CP could lead to the alteration in the expression of sarcomeric α-actin, α-actinin and mitochondrial UCP2. The different expressions of sarcomeric structure proteins and mitochondrial UCP2 may be involved in myocardial remodeling.
Actinin ; biosynthesis ; Actins ; biosynthesis ; Animals ; Cardiomegaly ; chemically induced ; metabolism ; pathology ; Cytokines ; adverse effects ; pharmacology ; Female ; Gene Expression Regulation ; drug effects ; Ion Channels ; biosynthesis ; Male ; Mice ; Mitochondrial Proteins ; biosynthesis ; Myocardium ; metabolism ; pathology ; Sarcomeres ; metabolism ; pathology ; Uncoupling Protein 2

OBJECTIVETo study the effect of Danshensu (DSS) and Ligustrazine (TMZ), the extracts of Chinese herbs for promoting blood circulation, on angiotensin II (Ang II) induced myocardial hypertrophy and its related genes, and to explore the mechanisms of inhibitory effect.

METHODSAdopting one-step method, the total RNA of myocardial cells was extracted by TRIzol reagent. Then the expression of ANP and beta-actin mRNA, as symbol of myocardial cells, were detected by RT-PCR.

RESULTSMolecular biological research showed that Ang II could significantly increase the expression of ANP mRNA in myocardial cells (P < 0.01), which could be significantly inhibited by Losartan (P < 0.01), both DSS and TMZ had the inhibitory effect (P < 0.05). Ang II could increase beta-actin mRNA expression in myocardial cells simultaneously, Losartan, DSS and TMZ could also significantly inhibit it (P < 0.05).

CONCLUSIONThe effective ingredients of Chinese herbs for promoting blood circulation, DSS and TMZ, have the effect of inhibiting the hyper-expression of ANP and beta-actin induced by Ang II, and preventing myocardial hypertrophy, therefore, it could be used to prevent and treat cardiomegaly.

Angiotensin II ; Animals ; Animals, Newborn ; Atrial Natriuretic Factor ; biosynthesis ; genetics ; Cardiomegaly ; chemically induced ; metabolism ; Cells, Cultured ; Drugs, Chinese Herbal ; pharmacology ; Female ; Lactates ; pharmacology ; Male ; Myocytes, Cardiac ; cytology ; metabolism ; Pyrazines ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Wistar

OBJECTIVE: To investigate the effects of hydrogen sulfide (HS) on the negatively regulation of cardiomyocyte hypertrophy and the relationship between the effect of HS with miRNA-133a-mediated Ca/calcineurin/NFATc4 signal pathway. METHODS: Cardiomyocyte hypertrophy was induced by isoproterenol (ISO). The cell surface area was measured by image analysis system (Leica). The expression of brain natriuretic peptide(BNP), β-myosin heavy chain(β-MHC), cystathionase (CSE), miRNA-133a, calcineurin (CaN) were detected by qRT-PCR. The protein expressions of CaN、nuclear factors of activated T cells (NFATc4) were detected by Western blot. The concentration of HS in the cardiomyocyte was detected by Elisa. The concentration of intracellular calcium was measured by calcium imaging using confocal microscope. The nuclear translocation of NFATc4 was checked by immuno-fluorescence cell staining technique. RESULTS: ①The level of system of CSE/HS and expression of miRNA-133a were significantly reduced in cardiomyocyte hypertrophy. Pretreatment with NaHS increased the concentration of HS and the expression of miRNA-133a mRNA in cardiomyocytes, and suppressed cardiomyocyte hypertrophy. ②The concentration of intracellular calcium, the expression of CaN and nulear protein NFATc4 were significantly increased, and the nuclear translocation of NFATc4 were obviously enhanced in cardiomyocyte hypertrophy. NaHS pretreatment markedly inhibited these effects of ISO induced cardiomyocyte hypertrophy. ③Application of antagomir-133a reversed the inhibitory effects of NaHS on cardiomyocyte hypertrophy, and increased the influx of intracellular calcium, and elevated the expression of CaN and nuclear protein NFATc4, and enhanced the nuclear translocation of NFATc4. CONCLUSIONS HS can negatively regulate cardiomyocyte hypertrophy. The effects might be associated with HS increasing expression of miRNA-133a and inhibiting inactivation of Ca/calcineurin/NFATc4 signal pathway.
Animals ; Calcineurin ; metabolism ; Cardiomegaly ; chemically induced ; metabolism ; Cells, Cultured ; Cystathionine gamma-Lyase ; metabolism ; Hydrogen Sulfide ; metabolism ; MicroRNAs ; metabolism ; Myocytes, Cardiac ; metabolism ; Myosin Heavy Chains ; metabolism ; NFATC Transcription Factors ; metabolism ; Natriuretic Peptide, Brain ; metabolism ; Nerve Tissue Proteins ; metabolism ; Rats ; Signal Transduction

BACKGROUNDThe Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway and the extracellular signal-regulated kinases 1/2 (ERK1/2) pathway are the two major independent signal transduction pathways. However, it has recently been found that STAT3 may be negatively regulated by ERK1/2 in gp130-dependent signaling. Cardiotrophin-1 (CT-1), a potent novel hypertrophic cytokine, depends on gp130 to induce signaling and depends on STAT3 to exert hypertrophic effect. In this study, we examined whether STAT3 activity was negatively regulated by ERK1/2 during CT-1-induced signaling in rat cardiomyocytes and, if so, whether such crosstalk interfered with the hypertrophic effect of CT-1 and, furthermore, whether the mechanism underlying the crosstalk involved phosphorylation of serine 727 (S727) in STAT3.

METHODSThe activities of ERK1/2 and STAT3 were assessed by in-gel kinase assay and Western blot analysis, respectively. The role of S727 phosphorylation in the crosstalk between ERK1/2 and STAT3 was determined by a transient transfection study using a STAT3S727A mutant. Cardiomyocyte hypertrophy was evaluated by the cellular protein-to-DNA ratio and [(3)H]-leucine incorporation.

RESULTSCT-1 simultaneously activated both ERK1/2 and STAT3 in rat cardiomyocytes. Inhibition of ERK1/2 by U0126 resulted in an increase of CT-1-induced tyrosine phosphorylation of STAT3 and, consequently, the protein-to-DNA ratio and [(3)H]-leucine incorporation. Transient transfection of the cells with STAT3S727A had no significant effect on CT-1-induced tyrosine phosphorylation of STAT3.

CONCLUSIONSSTAT3 is activated by CT-1 in rat cardiomyocytes, but full activation is mitigated by the simultaneous activation of ERK1/2. The inhibition of ERK1/2 increases the activity of STAT3, which, in turn, enhances the hypertrophic effect of CT-1. The crosstalk between ERK1/2 and STAT3 is independent of the phosphorylation of the S727 in STAT3. Such crosstalk may contribute to the development of adequate cardiac hypertrophy.

Active Transport, Cell Nucleus ; Animals ; Antigens, CD ; metabolism ; Cardiomegaly ; chemically induced ; metabolism ; Cytokine Receptor gp130 ; Cytokines ; toxicity ; DNA-Binding Proteins ; physiology ; Membrane Glycoproteins ; metabolism ; Mitogen-Activated Protein Kinase 1 ; physiology ; Mitogen-Activated Protein Kinase 3 ; physiology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; STAT3 Transcription Factor ; Trans-Activators ; physiology ; Tyrosine ; metabolism

OBJECTIVETo investigate the changes of proto-oncogene c-fos, c-jun mRNA expression in angiotensin II (Ang II)-induced hypertrophy and effects of tanshinone II A (Tan) in the primary culture of neonatal rat cardiomyocytes.

METHODTwelve neonatal Wistar rats aged one day old of clean grade and both sexes were selected to isolate and culture cardiomyocytes. The cardiomyocytes were divided into: normal control group, Ang II (10(-6) mol x L(-1)) group, Ang II (10(-6) mol x L(-1)) +Tan (10(-8) g x L(-1)) group, Ang II (10(-6) mol x L(-1)) + valsartan (10(-6) mol x L(-1)) group, Tan (10(-8) g x L(-1)) group, valsartan (10(-6) mol x L(-1)) group. The cardiomyocyte size was determined by phase contrast microscope, the rate of protein synthesis in cardiomyocytes was measured by 3H-leucine incorporation. The c-fos, c-jun mRNA expression of cardiomyocytes were assessed using reverse transcription polymerase chain reaction (RT-PCR).

RESULTAng II was added to the culture medium and 30 min later, the c-fos, c-jun mRNA expression of cardiomyocytes increased significantly (P < 0. 01). After Ang II took effect for 24 h, the rate of protein synthesis in Ang II group increased more prominently than that in normal control group (P < 0.01). After Ang II took effect for 7 days, the size of cardiomyocyte in Ang II group increased obviously (P < 0. 05). If tanshinone II or valsartan was added to the culture medium before Ang II, both of them could inhibit the increase of c-fos, c-jun mRNA expression (P < 0.01), cardiomyocyte protein synthesis rate (P < 0.01), and cardiomyocyte size (P < 0.05) induced by Ang II.

CONCLUSIONTanshinone II could ameliorate Ang II-induced cardiomyocytes hypertrophy by inhabiting c-fos, c-jun mRNA expression.

Angiotensin II ; biosynthesis ; pharmacology ; Animals ; Cardiomegaly ; chemically induced ; metabolism ; pathology ; Diterpenes, Abietane ; Gene Expression Regulation ; drug effects ; Genes, fos ; genetics ; Genes, jun ; genetics ; Myocytes, Cardiac ; drug effects ; metabolism ; pathology ; Phenanthrenes ; pharmacology ; Proto-Oncogene Proteins c-fos ; genetics ; Proto-Oncogene Proteins c-jun ; genetics ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Wistar ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

AIMTo investigate the effect of NOS and PTEN on the hypertrophic response induced by angiotensin II in the primary culture of neonatal rat cardiomyocytes.

METHODSTotal protein content of cardiomyocytes was used as the index of cardiac myocyte hypertrophy. eNOS mRNA, iNOS mRNA and PTEN mRNA expression were assessed using RT-PCR normalized with GAPDH. PTEN protein was determined by Western blot and immunohistochemistry method.

RESULTS(1) On day 1 after Ang II treatment, the expression of eNOS mRNA was significantly decreased whereas iNOS mRNA expression was significantly increased. The effect of Ang II on NOS expression was inhibited by L-arginine. (2) Total protein content of cardiomyocytes increased significantly on day 5 after Ang II treatment, and PTEN protein expression was significantly decreased. The increased protein content and the decreased expression of PTEN protein were inhibited by L-Arg. The L-arginine effect was blocked by L-NAME(NOS inhibitor). (3) The positive immunocytochemical product of PTEN was mainly located in the nucleus of myocardiocyte.

CONCLUSIONThese results indicate that NOS and PTEN may take part in the process of cardiac myocyte hypertrophy induced by Ang II. The effect of L-arginine on cardiomyocytes may be mediated by NOS/NO and PTEN.

Angiotensin II ; pharmacology ; Animals ; Animals, Newborn ; Cardiomegaly ; chemically induced ; metabolism ; pathology ; Cells, Cultured ; Myocytes, Cardiac ; drug effects ; metabolism ; pathology ; Nitric Oxide Synthase Type II ; metabolism ; Nitric Oxide Synthase Type III ; metabolism ; PTEN Phosphohydrolase ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley