| Objective To investigate the protective effects of preadministration of puerarin in different doses on pituitrin(Pit)-induced myocardial ischemia and lesion in rats.Methods 30 male SD rats weighted about 200 grammes were randomly divided into 5 groups,named N, C, P1,P2, P3. Rats of N for normal control group and those of C for positive control group were administrated 1ml/d of 0.9% sodium chloride by intraperitoneal injection. While rats of P1, P2, P3 , served as positive experimental groups, were administrated puerarin diluted to 1ml (puerarin of 50g/kg·d, 250g/kg·d, 500g/kg·d, respectively). Two hours after the 5th administration, Pit, at dose of 20u/kg, was intraperitoneal injected to rats of C, P1, P2, P3 groups, except for those of N group. A serials of body Ⅱ lead electrocardiogram(ECG) were recorded before the injection of Pit and at the time-point of 5min, 10min, 15min, 20min, 30min, 40min, 50min, 60min after the injection. The changes of J-point of ECG were measured. The thorax was cut open under aseptic condition to expose the heart. The whole blood was drawed out from ventricle to make the rats die. 2 ml of blood of each was saved for the measurement of serum cardiac troponin I(cTnI ). Then the heart was dissociated with pericardial membrane removed. Myocardial tissue below atrioventricular sulcus was transversely cut into two pieces for assessment of histological lesion by HE staining and ET-1 mRNA expres -sion by semiquantitative reverse transcription polymerase chainreaction (SQRT-PCR). Result (1) At the time 15 min after injection of Pit, J points markedly elevated/or fell down in rats in C groups comparaed with those in N group(2.52±0.65 vs 0.32±0.11 mm). The changed values of J points in P1, P2, P3 groups were 1.38±0.55, 0.98±0.54, 0.88±0.56, respectively, all showed significant difference comparaed with those in C group (P <0.05). (2) The serum cTnI was highest in C group,while the lowest in N group(24.33±5.45 vs 3.49±3.87 ng/ml, P<0.001). However, those values of P1, P2, P3 groups were 17.32±4.37, 13.54±6.76 ng/ml, 12.28±3.28 ng/ml, respectively, which could be seen the significant difference when compared with those in C group(P<0.05). In addition, a marked diffenence was observed between P1 and P3 groups (P<0.05). (3) A Pit-induced typical histological lesion of myocardial tissue was observed in C group, such as congestion, edema, a disorganization of myocytes and focal necrosis. The same changes were observed in P1, P2, P3 groups but less severe than in C group. (4) The ET-1 mRNA expression was strongly elevated in C group when compared with in N group (36549.57±36198.46 vs 13876.64±2523.86, P< 0.001). The mean gray degree values in P1,P2,P3 groups were 52353.42±8758.22, 68514.66±9864.56, 59953.95±6691.34, respectively, all were much less than those in C group(P< 0.05), but no differences were observed among themselves. Conclusion (1) Myocardial ischemia and lesion can be induced by intraperitoneal injection of Pit in rats. (2) Puerarin can attenuate, such as recovering the changed ST segment, decreasing serum cTnI and protecting the integrity of myocyte. (3) Puerarin can reduce ET-1 gene expression in myocardial tissue induced ischemia by Pit. |
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