Effects of tetramethylpyrazine on angiotensin II-induced proliferation and type I collagen synthesis of rat cardiac fibroblasts

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 μmol/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 μmol/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(P0.05) . Both optical densities of CFBs cultured with 0.1 μmol/L Ang Ⅱ plus 800 μg/mL TMP and 0.1 μmol/L Ang Ⅱ plus 600 μg/mL TMP were lower than that of CFBs cultured with 0.1 μmol/L Ang Ⅱ,but only the difference between 0.1 μmol/L AngⅡ plus 800 μg/mL TMP group and 0.1 μmol/L Ang Ⅱ group was significant(P0.05) .(2) The content of type Ⅰ collagen secreted by CFBs cultured with 0.1 μmol/L Ang Ⅱ was higher than that with 2% FBS-DMEM(P0.01) . The content of type Ⅰ collagen secreted by CFBs cultured with 0.1 μmol/L Ang Ⅱ plus 800 μg/mL TMP was lower than that with 0.1 μmol/L Ang Ⅱ(P0.05) .(3) The level of type Ⅰ collagen mRNA in 0.1 μmol/L Ang Ⅱ group was higher than that in blank control group,and lower than that in 0.1 μmol/L Ang Ⅱ plus 800 μg/mL TMP group. Both the differences between 0.1 μmol/L Ang Ⅱ group and the blank control group and between 0.1 μmol/L Ang Ⅱ group and 0.1 μmol/L Ang Ⅱ plus 800 μg/mL TMP group were statistically significant(P0.05) .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.