The Inhibitive Effect Of VNP On The Growth Promoting Role Of Hypoxia In Cardiac Fibroblasts

The chief aim of this study was to observe the effects of VNP on the proliferation, cell cycle phase, intracellular Ca2+ level and c-fos oncogene expression of hypoxia stimulated cardiac fibroblasts (CFs) of neonatal SD rats by means of cell culture, MTT method and the incorporation of 3H-TdR were applied. Furthermore, the effects of VNP on the intracellular level of Ca2+ and c-fos oncogene expression were performed to elucidate the mechanism of effects by the means of interactive laser cytometer and immunocytochemisty.1. Effect of VNP on the proliferation of CFsstimulated by hypoxia.Hypoxia(20 ml/L~30 ml/I) stimulated the growth of CFs. OD value of hypoxia group was remarkably higher than that of the control group (P<0.05). VNFdO^條O'6 mol/L) inhibited the growth of CFs stimulated by hypoxia. OD value of VNP+ hypoxia group was lower than that of the hypoxia-4-group (P<0.05).2. Effect of VNP on the cell cycle of CFs underhypoxiaFlow cytometric DNA analysis revealed the VNP(1CT6 mol/L) could reverse the effect induced by hypoxia. VNP could inhibit the quiescent cell from GO/G1 phase into S phase. It enhanced GO/G1 phase of CFs and decreased G2/M phase of CFs (P<0. 01).3. Effect of VNP on the 3H-TdR incorporation in CFsstimulated by hypoxia.Hypoxia(20 ml/L ~ 30 ml/L) increased 3H-TdR incorporation in CFs. VNP could decrease 3H~TdR incorporation in CFs in a concentration-dependent manner. 3H-TdR incorporation value of 10-8, 10-7 mol/L and 10"6 mol/L VNP groups which were (105 + 8) %cpm, (95 + 14) %cpm, (81 + 7) %cpm, respectively were significantly lower than that of hypoxia group (KO. 05)4. Effect of VNP and hypoxia on the intracellular Ca2+level in CFsHypoxia increased the intracellular level of Ca2+ significantly. VNP(10~6 mol/L) decreased the intracellular level of Ca2+ which was increased by hypoxia(/XO. 05 )as compared with hypoxia group.-5-5. Effect of VNP on the c-fos oncogene expressionin CFs stimulated by hypoxia.Hypoxia increase the c-fos oncogene expression in CFs. VNP(10-6 mol/L) attenuated this effect of hypoxia.These results suggested that VNP could attenuate the growth-promoting role of hypoxia in CFs . Its mechanism might be due to changes of the intracellular Ca2+ level and c-fos oncogene expression.