Objective    To investigate the effects of oxidized low density lipoprotein (ox-LDL) on collagen synthesis and degradation in cultured cardiac fibroblast of neonatal SD rat.     Methods    Cardiac fibroblast of neonatal SD rat was primarily cultured and treated with ox-LDL (10

20

50 and 100 μg/ml）for 24 h. DNA synthesis was measured by

3

H-TdR incorporation and collagen synthesis was measured by

3

H-Proline incorporation. Matrix metalloproteinase (MMPs) activity was measured by gelatinase

zymography. Protein levels of MMP-2 and MMP-9 were measured by Western blot. MMP-2 and MMP-9 mRNA expressions were detected by RT-PCR.     Results    After 24-hour treatment with ox-LDL

DNA synthesis was increased in a collagen decreased way and the collagen synthesis was significantly decreased at the same time. It also showed  ox-LDL significantly increased MMPs activities

but had no difference between different concentration groups. The protein contents of  MMP-2 and MMP-9 in condition media were significantly increased after treated with ox-LDL

and the effect of 100 μg/ml was the most obvious. The mRNA expressions of MMP-2 and MMP-9 were also significantly increased by 50 μg/ml and 100 μg/ml ox-LDL.     Conclusion    ox-LDL decreases collagen synthesis and increases collagen degradation. It may be involved in the process of post-myocardial infarction ventricle remodeling.