Objective: To observe the effects of tetramethylpyrazine (TMP) on the proliferation and type I collagen synthesis of rat cardiac fibroblasts (CFBs) induced by angiotensin II (Ang II), and to explore the mechanism of TMP in treating myocardial fibrosis.
Methods: CFBs were isolated from neonatal rats, and the fourth-passage CFBs were used in the entire test and were stimulated by 0.1 micromol/L Ang II in vivo. The CFB proliferation was measured by methyl thiazolyl tetrazolium (MTT) assay. Type I collagen in the cell culture supernatant was measured by enzyme-linked immunosorbent assay. The expression of mRNA of type I collagen was semi-quantitatively measured by reverse transcription-polymerase chain reaction (RT-PCR).
Results: (1) In MTT assay, the optical density of CFBs cultured with 0.1 micromol/L Ang II was higher than that of the blank control cultured with 2% fetal bovine serum-Dulbecco's modified Eagle's medium (FBS-DMEM). The difference was statistically significant (P < 0.05). Both optical densities of CFBs cultured with 0.1 micromol/L Ang II plus 800 microg/mL TMP and 0.1 micromol/L Ang II plus 600 microg/mL TMP were lower than that of CFBs cultured with 0.1 micromol/L Ang II, but only the difference between 0.1 micromol/L AngII plus 800 microg/mL TMP group and 0.1 micromol/L Ang II group was significant (P < 0.05). (2) The content of type I collagen secreted by CFBs cultured with 0.1 micromol/L Ang II was higher than that with 2% FBS-DMEM (P < 0.01). The content of type I collagen secreted by CFBs cultured with 0.1 micromol/L Ang II plus 800 microg/mL TMP was lower than that with 0.1 micromol/L Ang II (P < 0.05). (3) The level of type I collagen mRNA in 0.1 micromol/L Ang II group was higher than that in blank control group, and lower than that in 0.1 micromol/L Ang II plus 800 microg/mL TMP group. Both the differences between 0.1 micromol/L Ang II group and the blank control group and between 0.1 micromol/L Ang II group and 0.1 micromol/L Ang II plus 800 microg/mL TMP group were statistically significant (P < 0.05).
Conclusion: TMP can not only inhibit the proliferation of CFBs, but also decrease the secretion and the mRNA expression level of collagen I in cultured CFBs of rat which are increased by Ang II.