Effects of alpha adrenergic blockade during stellate ganglion stimulation on arrhythmias induced by acute myocardial ischemia in pigs

Summary The effects of α-adrenergic receptor blockade during stellate ganglion stimulation on arrhythmias induced by repeated coronary artery occlusion in pigs under spontaneous breathing were studied. Prazosin, α₁-receptor blocker, did not have any effect on the early ischemic dysrhythmia. Yohimbin, which selectively blocks α₂-receptor, significantly increased the number of premature ventricular complexes (19±3→ 32±2 PVC;P<0.01), but produced no effects on the percentage of appearance of ventricular fibrillation (VF) and ventricular tachycardia (VT). However, nonselective α-receptor blocker phentolamine significantly reduced the number of premature ventricular complexes (30.5 ± 4.5→ 11 ±3 PVC;P<0.05), but did not affect the frequency of occurrence of VF and VT. The above results show that α-adrenergic mechanisms do not play any important role in the genesis of arrhythmias during ischemia in the pig model.     

家兔孤束核连合亚核注射去甲肾上腺素对肾神经放电频率的影响

向家兔孤束核连合亚核(CNTS)注射去甲肾上腺素(NE),明显衰减肾神经放电频率(FRND),同时降低平均动脉血压(MAP);经相关分析,所导致的FRND和MAP的变化呈显著正相关;预先向CNTS内注射α_2受体阻断剂育亨宾,本身对FRND和MAP无显著影响,但可阻断甚至逆转NE在CNTS中降低FRND及MAP的效应。结果提示NE在CNTS内激活α_2受体后,通过减弱外周交感张力而产生降压效应。