摘要
比较了外源性腺苷(1μmol/kg,iv)、迷走神经刺激(30 Hz,4 V,0.1 ms,10s)及缺氧(2％O_2,10 min)对豚鼠心脏(n=52)的作用,发现3者均引起窦性周期延长、房室传导时间延长及房室传导阻滞,阻滞部位都在房室结近端AH段。氨茶碱(5 mg/kg,iv)可以拮抗外源性腺苷的作用;刺激左迷走神经外周端不伴有心肌内源性腺苷含量增加;缺氧时心肌内源性腺苷含量大幅度增加,动物阿托品化(0.2mg/kg,iv)未阻断缺氧引起的心律失常及心肌腺苷含量增加。实验结果提示:高腺苷含量及高迷走神经张力均可以起窦性心率减慢及房室传导阻滞。
Experiments were performed to compare the effects of exogenous adenosine (1 μmol/ kg ,i v), vagal stimulation (30 Hz, 4 V, 10 ms) and hypoxia ( 20%O_2, 10 min ) on guinea pig hearts (n=52). It was observed that all of these intervents caused prolongation of sinus cycle length, A-V conduction time and even high degree of A-V block. The site of block was all localized in the proximal portion of the AVN region. Aminophylline (5 mg/kg,iv) antago- nised the effects of adenosine. Vagal stimulation did not result in the increases in contents of myocardial adenosine occurred during hypoxia. Neither arrhythmias nor myocardial adeon- sine increases caused by hypoxia were blocked by atropinization(0. 2 mg/kg, iv). We con- clude that both high myocardial adenosine level and high vagal tone may result in sinus bradycardia and A-V block.
关键词
腺苷
迷走神经
氨茶碱
心肌缺氧
adenosine
vagal nerve
aminophylline
atropine
myocardial hypoxia
