s AIM: To investigate the protective effects of xinmai tong on acute
myocardial ischemic injury induced by isoproteronol
(IP) in rats. METHODS: The experiment was completed in the Central Laboratory of Medical College of Jinan University from November to December 2005. ① Totally 24 healthy SD rats of clean grade and either gender were selected and divided randomly into control group, model group, high-dosage xinmai tong group and low-dosage xinmai tong group with 6 in each group. According to body surface area (10 mL/kg), rats in low- and high-dosage
groups were perfused with 162 and 324 mg/(kg·d) xinmai tong, respectively, which was mixed with distilled water. Rats in control group and model group were perfused with the same volume of saline once a day for 7 successive days. ② 30-60 minutes after the last administration, rats except control group were anesthetized and injected with 4 mg/(kg·d) IP subcutaneously at various sites for 2 days to establish models of acute
myocardial ischemia. Excursion at J site of electrocardiograph (ECG) ≥ 0.1 mV was regarded at successful modeling. ③ Excursion at ST-junction (J site) of ECG was detected 30 minutes and 12 hours after IP injection with BL-420E biological function experimental system; activities of serum creatine kinase (CK), creatine kinase isoenzyme (CK-MM) and lactate dehydrogenase (LDH) were assayed with enzyme method; level of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were assayed with TBA method and xanthine oxidase method, respectively. ④ Averages were compared with single-factor analysis of variance and q test among groups. RESULTS: Totally 24 rats entered the final analysis. ① Excursion degree at J site was higher in model group than that in control group, high- and low-dosage xinmai tong groups 30 minutes and 12 hours after IP injection (P < 0.05). ② Activities of serum CK, CK-MM and LDH were higher in model group than those in control group, low- and high-dosage xinmai tong groups (P < 0.05). ③ SOD activity in model group was lower than that in control group, low- and high-dosage xinmai tong groups (P < 0.05), but MDA level was higher than that in control group, low- and high-dosage xinmai tong groups (P < 0.05). CONCLUSION: Xinmai tong can protect myocardial ischemic injury induced by IP, which is probably related with improving myocardial ischemia, reducing production of free radical, and increasing activity of anti-oxidase.