RESUMO
<p><b>AIM</b>To observe the effects of hypoxia on DNA synthesis and the expression of collagen type I and III mRNA in cultured adult rat cardiac fibroblasts.</p><p><b>METHODS</b>Cardiac fibroblasts(CFs) were isolated from adult Wistar rat ventricule and cultured in vitro either in normoxic or hypoxic condition. Studies were conducted with the second passage of CFs. The changes of DNA synthesis was determined by measuring the incorporation of 3H-TdR into DNA and the changes of expression of pro-alpha1 (I) collagen, pro-alpha1(III) mRNA were measured by in situ hybridization respectively.</p><p><b>RESULTS</b>The 3H-TdR incorporation of CFs was increased by 34% (P < 0.05) and 36% (P < 0.01) after 6 h, 12 h hypoxia (2% O2) exposure respectively. The level of pro-alpha1(I) collagen mRNA expression was significantly elevated in the cells under hypoxia for 4 h, 8 h, and 12 h. The expression of pro-alpha1(III) mRNA increased when cells were cultured under hypoxia for 2 h.</p><p><b>CONCLUSION</b>These results suggest that hypoxia alone can upregulate DNA synthesis and expression of collagen type I and III mRNA in adult rat cardiac fibroblasts. It may be one of the important mechanisms by which hypoxic myocardial fibrosis occur.</p>