Objective: To study the protective effects of Dahuang Zhechong Pill (DHZCP) on myocardial fibrosis induced by isoprenaline (Iso) in rats. Method: Fifty SD rats were divided into 5 groups randomly: normal control

model control

positive control (Danshen

1 g·kg-1·d-1)

low and high doses of DHZCP (1.6

3.2 g·kg-1·d-1). Myocardial fibrosis model was established by subcutaneous injection of 5 mg·kg-1Iso in rats for 10 days except normal control rats. The drugs were administered intragastrally to rats for 28 days. The histopathological change was examined

and level of hydroxyproline and malondialdehyde (MDA) as well as superoxide dismutase (SOD) activity were determined in the myocardial tissue. Result: The results showed that heart index

level of hydroxyproline and MDA

collagen volume fraction (CVF)

perivascular collagen area (PVCA) were increased

and SOD activity was reduced in myocardial tissue of model rats in comparison with normal rats. The histopathological examination showed that there was a significant collogen proliferation and myocardial fibrosis. However

DHZCP improved and reversed the changes induced by Iso. Conclusion: DHZCP is able to reverse the myocardial fibrosis induced by Iso and to improve ventricular remodeling in rats

which may not related to antioxidative effect.