Total Flavonoids of Fructus Chorspondiatis inhibits collagen synthesis of cultured rat cardiac fibroblasts induced by angiotensin II: Correlated with NO/cGMP signaling pathway

Aim To investigate the molecular mechanism of Total Flavonoids of Fructus Chorspondiatis (TFFC) on preventing cardiac fibroblasts collagen synthesis induced by angiotensin II. Methods Collagen synthesis was determined by measuring ³H-proline incorporation cardiac fibroblasts and hydroxyproline content in the culture mediums. The expression of collagen types I and III mRNA and protein was measured by RT–PCR and western blot, respectively. NO level in the culture medium was measured by the Griess reagent. NOS level in the culture medium was measured by chemical colorimetric method. The cellular concentration of cyclic GMP (cGMP) was measured by radioimmunoassay. Results TFFC (25, 50, and 100mg/L) inhibited collagen synthesis in cardiac fibroblasts in a dose-dependent manner compared with angiotensin II group (P <0.01), and the inhibitory effects were blocked by pretreatment with NG-nitro-l-arginine methyl ester (L-NAME) and 1H-[1,2,4]-oxadiazole-[4,3-a]-quinoxalin-1-one (ODQ). TFFC increased nitric oxide (NO) and nitric oxide synthase (NOS) levels in the culture medium, increased intracellular cGMP level in cardiac fibroblasts, decreased collagen types I and III protein level in cardiac fibroblasts. The mRNA expression of collagen type I and III was suppressed by TFFC. Conclusions These results suggested that TFFC inhibited collagen synthesis induced by angiotensin II in cardiac fibroblasts, and the inhibitory effect might associate with the activation of the NO/cGMP signaling pathway.