Cardiomyocytes isolated from neonatal rats were treated with phorboll 2-myristatel 3-acetate (PMA ) ranging from 10(-11)to 10-7 mol/L for 20 min, causing cytosol protein kinase A (PKA) activity to decrease while parti...Cardiomyocytes isolated from neonatal rats were treated with phorboll 2-myristatel 3-acetate (PMA ) ranging from 10(-11)to 10-7 mol/L for 20 min, causing cytosol protein kinase A (PKA) activity to decrease while particulate PKA activity increase in a concentration-dependent manner. The change of PKA activity induced by PMA was abolished completely by pretreatment of polymyxin B or depletion of protein kinase C (PKC). Type II PKA activity in particulate fraction was enhanced remarkably, while that of type I PKA was not altered when the cells were treated with 100 nmol/L PMA. The results suggested that subcellular distribution and activity of PKA in cardiomyocytes may be regulated by PKC.展开更多
OBJECTIVE: To study the changes in activity of phosphatidylinositol 4 kinase (PI 4 kinase), phosphatidylinositol 4 phosphate 5 kinase (PIP 5 kinase) and protein kinase C (PKC) during myocardial ischemia and elucidate ...OBJECTIVE: To study the changes in activity of phosphatidylinositol 4 kinase (PI 4 kinase), phosphatidylinositol 4 phosphate 5 kinase (PIP 5 kinase) and protein kinase C (PKC) during myocardial ischemia and elucidate the relationship between phosphatidylinositol signal pathways and prolonged myocardial ischemia. METHODS: In vivo an ischemic rat model was used. Activity of PI 4 kinase, PIP 5 kinase and PKC were measured at different times in postischemic heart cells using isotope analysis. RESULTS: The activity of PI kinase, PIP kinase and PKC in the myocardium increased to peak at 1 hour postischemia, with activities 6.1, 3.0 and 4.0 fold over control levels, respectively. Their activities declined to normal levels with time. CONCLUSION: The phosphatidylinositol signal pathway is involved in prolonged myocardial ischemia, but its mechanism needs further study.展开更多
Objective： Vascular endothelial growth factor （VEGF） plays important roles in establishing collateral circulation of ischemic myocardium. This study aimed to investigate the effect of isoflurane on VEGF expression ...Objective： Vascular endothelial growth factor （VEGF） plays important roles in establishing collateral circulation of ischemic myocardium. This study aimed to investigate the effect of isoflurane on VEGF expression and the potential intracellular signal transduction pathway in cultured rat myocardial cells in order to further reveal the molecular mechanism of myocardial preservation of isoflurane. Methods： Primary myocardial cells of Sprague-Dawley rats were isolated and cultured. They were divided randomly into control group, isoflurane group, protein kinase C （PKC） inhibitor group and PKC inhibitor＋isoflurane group where cells were respectively incubated without any treatment, treated by 0.5, 1.0 and 1.5 minimum alveolar concentration （MAC） of isoflurane for 6 hours, by PKC inhibitor calphostin C at a final concentration of 50 nmol/L and by 50 nmol/L calphosfin C＋ 1.0 MAC isoflurane for 6 hours. VEGF expression was detected by enzyme-linked immunosorbent assay （ELISA） and the expression levels of PKC isoforms were determined by Western immunoblotting method. Results： Isoflurane increased the VEGF expression in myocardial cells in a dose-dependent way. VEGF levels were significantly higher in 1.0 and 1.5 MAC isoflurane groups than in the control group （both P〈0.01）. The effect of isoflurane on upregulating VEGF expression was blocked by PKC inhibitor calphostin C （P〈0.01）, but calphostin C did not alter VEGF expression （P〉0.05）. Isoflurane induced the activation and translocation of PKC Immunoblotting analysis revealed that the immunoreactivity of PKC ε increased significantly in the membrane fractions and deceased significantly in the kytoplasm fractions for cells treated with 1.0 MAC isoflurane as compared with the untreated cells, but not of PKC a, PKCα and PKCζ （P〈0.01）. Conclusion： Isoflurane induces myocardial cells to release VEGF through activating PKCε from the endochylema to the cytomembrane, suggesting a possible novel mechanism of isoflurane protecting myocardial cells.展开更多
文摘Cardiomyocytes isolated from neonatal rats were treated with phorboll 2-myristatel 3-acetate (PMA ) ranging from 10(-11)to 10-7 mol/L for 20 min, causing cytosol protein kinase A (PKA) activity to decrease while particulate PKA activity increase in a concentration-dependent manner. The change of PKA activity induced by PMA was abolished completely by pretreatment of polymyxin B or depletion of protein kinase C (PKC). Type II PKA activity in particulate fraction was enhanced remarkably, while that of type I PKA was not altered when the cells were treated with 100 nmol/L PMA. The results suggested that subcellular distribution and activity of PKA in cardiomyocytes may be regulated by PKC.
基金the National Great Foundamental Research Proiect (No．G2000057004) the National Nature Science Foundation of China(No．19890308)．
文摘OBJECTIVE: To study the changes in activity of phosphatidylinositol 4 kinase (PI 4 kinase), phosphatidylinositol 4 phosphate 5 kinase (PIP 5 kinase) and protein kinase C (PKC) during myocardial ischemia and elucidate the relationship between phosphatidylinositol signal pathways and prolonged myocardial ischemia. METHODS: In vivo an ischemic rat model was used. Activity of PI 4 kinase, PIP 5 kinase and PKC were measured at different times in postischemic heart cells using isotope analysis. RESULTS: The activity of PI kinase, PIP kinase and PKC in the myocardium increased to peak at 1 hour postischemia, with activities 6.1, 3.0 and 4.0 fold over control levels, respectively. Their activities declined to normal levels with time. CONCLUSION: The phosphatidylinositol signal pathway is involved in prolonged myocardial ischemia, but its mechanism needs further study.
基金This study was supported by the National Natural Science Foundation of China （No. 30700789）.
文摘Objective： Vascular endothelial growth factor （VEGF） plays important roles in establishing collateral circulation of ischemic myocardium. This study aimed to investigate the effect of isoflurane on VEGF expression and the potential intracellular signal transduction pathway in cultured rat myocardial cells in order to further reveal the molecular mechanism of myocardial preservation of isoflurane. Methods： Primary myocardial cells of Sprague-Dawley rats were isolated and cultured. They were divided randomly into control group, isoflurane group, protein kinase C （PKC） inhibitor group and PKC inhibitor＋isoflurane group where cells were respectively incubated without any treatment, treated by 0.5, 1.0 and 1.5 minimum alveolar concentration （MAC） of isoflurane for 6 hours, by PKC inhibitor calphostin C at a final concentration of 50 nmol/L and by 50 nmol/L calphosfin C＋ 1.0 MAC isoflurane for 6 hours. VEGF expression was detected by enzyme-linked immunosorbent assay （ELISA） and the expression levels of PKC isoforms were determined by Western immunoblotting method. Results： Isoflurane increased the VEGF expression in myocardial cells in a dose-dependent way. VEGF levels were significantly higher in 1.0 and 1.5 MAC isoflurane groups than in the control group （both P〈0.01）. The effect of isoflurane on upregulating VEGF expression was blocked by PKC inhibitor calphostin C （P〈0.01）, but calphostin C did not alter VEGF expression （P〉0.05）. Isoflurane induced the activation and translocation of PKC Immunoblotting analysis revealed that the immunoreactivity of PKC ε increased significantly in the membrane fractions and deceased significantly in the kytoplasm fractions for cells treated with 1.0 MAC isoflurane as compared with the untreated cells, but not of PKC a, PKCα and PKCζ （P〈0.01）. Conclusion： Isoflurane induces myocardial cells to release VEGF through activating PKCε from the endochylema to the cytomembrane, suggesting a possible novel mechanism of isoflurane protecting myocardial cells.
