Inhibitory effects of rosiglitazone against endothelin-1-induced proliferation of rat cardiac myocytes: the role of PKC-c-fos pathway / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the mechanism of rosiglitazone (RSG, the activator of peroxisome proliferators activated receptor lambda) for inhibiting endothelin-1 (ET-1)-induced neonatal rat cardiac myocyte hypertrophy and the role of protein kinase C (PKC) and c-fos.</p><p><b>METHODS</b>In vitro cultured neonatal rat cardiac myocytes were treated with ET-1, phorbol ester (PMA, the PKC activator), ET-1+RSG, ET-1+chelerythrine (che, the PKC inhibitor), PMA+RSG, or without treatment (control), respectively. The effects of RSG on the protein content, (3)H-leucine incorporation, PKC activity and C-fos protein expression were observed in the cardiac myocytes stimulated with ET-1 or PMA.</p><p><b>RESULTS</b>After two days of culture, the intracellular protein content in ET-1 group and PMA group were increased by 15% (339-/+15 microg/ml) and 13% (329-/+14 microg/ml) as compared with the control cells (290-/+13 microg/ml), respectively (P<0.01). Compared with the ET-1 group, cells treated with ET-1+10(-8) mol/L RSG, ET-1+10(-7) mol/L RSG, and ET-1+che showed decreased intracellular protein content by 10% (303-/+14 microg/ml, P<0.05), 12% (292-/+11 microg/ml, P<0.05), and 13% (291-/+12 microg/ml, P<0.01), respectively. The intracellular protein content in PMA+10(-7) mol/LRSG group was decreased by 10% (P<0.05) in comparison with the PMA group. RSG inhibited protein synthesis enhancement and increased (3)H-leucine incorporation induced by ET-1 and PMA, and antagonized the effects of ET-1 and PMA in promoting PKC activity and c-fos protein expression in the myocytes.</p><p><b>CONCLUSION</b>The inhibitory effect of RSG on ET-1- or PMA-induced myocyte hypertrophy is associated with PKC-c-fos pathway.</p>

Relationship between cardiomyocyte protein synthesis and cell viability / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the relationship between protein sythesis and cardiomyocyte viability in neonatal rats.</p><p><b>METHODS</b>The protein sythesis in neonatal rat cardiomyocytes was measured according to Brandford's method, the absorbance at 490 nm (A(490 nm)) of the cells was measured with MTT assay and the cell viability evaluated by the ratio of A(490 nm) to the total cell number.</p><p><b>RESULTS</b>ET-1 increased cardiomyocyte protein synthesis dose-dependently, and this effect was attenuated by the application of lacidipine and tetramethylpyrazines Higher doses of ET-1 resulted in lower A(490 nm)/total cell number ratio, which was further lowered by larcidipine and tetramethylpyrazine.</p><p><b>CONCLUSION</b>The status of protein synthesis is not associated with the viability of neonatal rat cardiomyocytes.</p>

Analysis of inflammatory reaction of atherosclerosis model / 中国中药杂志

<p><b>OBJECTIVE</b>To analysis and evaluate the inflammatory reaction of atherosclerosis model in rabbits.</p><p><b>METHOD</b>A model of atherosclerosis in rabbits was estabalished by injury with balloon and high cholesterol diet to observe the dynamic change of serum inflammation markers c-reactive protein, interleukin-1beta and tumor necrosis factor-a, and the relationship between severity of AS lesion and those change.</p><p><b>RESULT</b>(1) The levels of TNF-alpha at 4 time points: 1, 6, 10 weeks and 10 weeks + 1 day after balloon injury increased 1.6-fold, 2.2-fold, 4-fold, 2-fold over concurrent control, respectively (P < 0.05, P < 0.01, P < 0.01, P < 0.01), but no significant changes occurred during the observation. (2) At the end of the 6, 10 weeks and 10 weeks + 1 day, the levels of CRP were increased 3.5-fold, 3.6-fold, 3.0-fold than concurrent control (P < 0.01, P < 0.01, P < 0.01), respectively. The levels were increased 2.4-fold at the end of the 6 weeks and 4.1-fold at the end of the 10 weeks and reached the peak compared with the point of 1 week. (3) TNF-alpha and CRP showed a significant positive correlation with the MIT (correlation coefficients were found to be 0.61, 0.64, P < 0.01). (4) At the end of the 1, 6, 10 weeks, the model was provided with general pathological characteristics and the inflammatory reaction of earlier inflammatory reaction phase, fatty streak plaques phase, fibrous plaque phase respectively.</p><p><b>CONCLUSION</b>The model was provided with early and medial phase typical feature of atherosclerotic lesion, and showed a significant positive correlation with the inflammatory factor expression. At the end of the 6 weeks, the formation of fatty streak plaques and obvious inflammatory reaction could be satisfied for the interference in forming process of AS from dimension of inflammatory and screening assays of drugs.</p>

Protective effects of nitric oxide donor on hydrogen peroxide-induced injury of cardiomyocytes / 生理学报

To investigate the protective effects of nitric oxide (NO) on cardiomyocytes against hydrogen peroxide (H2O2)-induced injury, cultured neonatal cardiomyocytes were divided into three groups: (1) normal group; (2) H2O2 group: cells were treated with H2O2 (0.1 mmol/L) for 4 h; (3) SNAP+ H2O2 group: cells were pretreated with NO donor S-nitroso-N-acetyl-1,1-penicillamine (SNAP, 0.5 mmol/L) 10 min before H2O2 treatment. Colorimetric assay was used to detect cell viability and lactate dehydrogenase (LDH) activity to evaluate cell injury. Apoptotic rate of cardiomyocytes were determined by flow cytometer. Superoxide dismutase (SOD) activity and malonaldehyde (MDA) content were measured by colorimetric assay to evaluate cell antioxidant ability. Intracellular calcium was tested by laser confocal microscopy. The results showed that after treatment with H2O2, cell viability was significantly reduced to 58.3+/-7.6% compared with normal group (93.1+/-6.2 %). LDH activity and apoptotic rates were 1580.5+/-186.7 U/L and 26.4+/-5.7% respectively, significantly higher than that of normal group (631.4+/-75.6 U/L and 0). SNAP pretreatment markedly improved cell viability to 79.7+/-9.3% and reduced LDH activity and apoptotic rates to 957.8+/-110.9 U/L and 9.1+/-3.3%, respectively. Cells treated with H2O2 had a lower SOD activity of 14.73+/-1.68 NU/ml and a higher MDA content of (15.35+/-3.49) micromol/L compared with normal cells (19.67+/-0.85 NU/ml) and (6.95+/-0.83 micromol/L), respectively. Cells with SNAP pretreatment had a higher SOD activity of 21.36+/-3.11 NU/ml and a lower MDA content of 9.12+/-1.47 micromol/L compared with H2O2 group. Intracellular calcium content was reduced by SNAP administration while enhanced by H2O2. Pretreatment with SNAP could antagonize the effect of H2O2 of accelerating intracellular calcium content. Based on the results observed, it is concluded that NO donor SNAP may protect cardiomyocytes from being injured by H2O2. The underlying mechanisms may include improving cell antioxidant ability and reducing intracellular calcium overload.