Chiba K, Hayase N, Ichihara K
Department of Hospital Pharmacy, Asahikawa Medical College, Japan.
J Pharm Sci. 1993 Apr;82(4):384-8. doi: 10.1002/jps.2600820410.
The effect of bunitrolol, a beta-adrenergic blocking agent having intrinsic sympathomimetic activity, on ischemic myocardial metabolism was examined in anesthetized dog hearts. Ischemia was induced by ligating the left anterior descending coronary artery for 3 or 30 min. Bunitrolol (0.3 or 1.0 mg/kg of body weight) was injected intravenously 5 min before the onset of ischemia. Ischemia reduced myocardial high-energy phosphate levels and changed the levels of glycolytic intermediates. Bunitrolol at a dose of 0.3 mg/kg significantly decreased heart rate, whereas the drug at a dose of 1.0 mg/kg did not. This result suggests that intrinsic sympathomimetic activity is observed only at a high dose of bunitrolol. Pretreatment with bunitrolol at 0.3 but not 1.0 mg/kg attenuated the myocardial metabolic changes caused by 3 min of ischemia. After 30 min of ischemia, a beneficial effect of bunitrolol on the ischemic myocardium was not observed. These results suggest that bunitrolol may lessen the ischemic influence on the myocardium in the early stage of ischemia and that intrinsic sympathomimetic action may not have a beneficial effect on the ischemic myocardium.
在麻醉犬心脏中研究了具有内在拟交感活性的β-肾上腺素能阻滞剂布尼洛尔对缺血心肌代谢的影响。通过结扎左冠状动脉前降支3分钟或30分钟诱导缺血。在缺血开始前5分钟静脉注射布尼洛尔（0.3或1.0毫克/千克体重）。缺血降低了心肌高能磷酸水平并改变了糖酵解中间产物的水平。剂量为0.3毫克/千克的布尼洛尔显著降低心率，而剂量为1.0毫克/千克的药物则没有。该结果表明仅在高剂量布尼洛尔时观察到内在拟交感活性。以0.3毫克/千克而非1.0毫克/千克的布尼洛尔预处理可减轻3分钟缺血引起的心肌代谢变化。缺血30分钟后，未观察到布尼洛尔对缺血心肌的有益作用。这些结果表明布尼洛尔可能在缺血早期减轻对心肌的缺血影响，并且内在拟交感作用可能对缺血心肌没有有益作用。
