米利酮对正常与心功能不全大鼠离体心肌作用的比较

目的和方法 :本试验通过肌张力测定和心肌细胞内cAMP蛋白结合分析法观察了不同剂量的米利酮对正常大鼠与心功能不全大鼠左心乳头肌的正性肌力作用。结果 :在正常大鼠与心功能不全大鼠米利酮均有肯定的正性肌力作用。在常规剂量组 ,心衰组心肌收缩力增加的幅度低于对照组 (P <0 .0 5 ) ,但在大剂量下两组心肌收缩力的增长的百分率相似 (P >0 .0 5 )。cAMP检测发现心衰组大鼠心肌细胞内cAMP水平低于对照组 ,常规剂量与高剂量米利酮作用下cAMP均明显升高 (P <0 0 1) ,但两个剂量组之间比较无显著差异 (P >0 0 5 )。实验还发现心衰组给予大剂量药物时正性肌力作用先于cAMP的升高。结论 :米利酮对病变和正常心肌的正性肌力作用存在一定差异 ,由于大鼠心功能不全发生后心肌细胞的病理改变 ,该药的正性肌力作用可能有其它机制参与。

COMPARISON OF POSITIVE INOTROPIC EFFECT OF MILRINONE ON MYOCARDIUM BETWEEN NORMAL AND CARDIAC DYSFUNCTIONAL RATS

Aim and Methods: To investigate the positive inotropic effect of milrinone on isolated cardiac papillary muscle of cardiac dysfunctional rat (CD group) and normal rat by means of the determination of the isometrtc force of cardi acmuscle and the analysis of cAMP protein overturn. Results:The drug casused definite increase of isometric force in capillary muscle from both normal and cardiac dysfunctional rats. The range of increase of isometric force is lower in CD group than that of control group after administration of routine dose of milrinone. However the percentage of increase of force was similar between two groups under the high dose of milrinone. The cAMP content of cardiac myocytes from CD group was lower than that of control group. After administration of drug, the level of cAMP in myocytes increased markedly in routine and high does group. No significant difference was found between two dose groups. However, it also showed that the increase in isometric force development preceded the increase of cAMP level in cardiac myocytes after administration of high dose of drug. Conclusion: There was difference of positive inotropic effect ot milrinone on myocardium between cardiac dysfunctional rat and normal rat. Because of the pathologic change of cardiac muscle of rat after heart fai lure, other mechanisms were involved possibly in the action of milrinone.