【摘要】 目的 研究不同浓度腺苷（Ado）对正常、“缺血”浦肯野纤维起搏离子流If的影响。方法 成年绵羊离体心室浦肯野纤维分为对照组、10^-6-10^-4mol/L Ado组、缺血加10^-6-10^-4mol/L Ado组。用双微电极电压钳制术,分别观察在膜电位-70-（-120mV）各指令电位的If幅值和激活时间。 结果 10^-6-10^-4mol/L Ado组If幅值降低,激活曲线向超极化方向移位,呈一定的剂量依赖性,但激活时间无明显改变。“缺血”液灌流后If幅值降低（n=10,P<0.05-0.01）,激活曲线向超极化方向移位,激活时间延长;缺血加10^-6-10^-4mol/L Ado组则If幅值进一步减少（n=10,P<0.05-0.01）,加剧了“缺血”对If离子流的抑制作用（n=10,P<0.05）,也呈一定的剂量依赖性。结论 10^-6-10^-4mol/L Ado对正常自律活动有抑制作用,呈一定的剂量依赖性,“缺血”时,10^-6-10^-4mol/L Ado能使已受抑的自律活动进一步受抑,也呈一定的剂量依赖性。更多还原

【Abstract】 Objective The purpose of this study was to observe the effects of 10 -6- 10-4mol/L adenosine （Ado） , a main metabolite in acute ischernic myocardium, on pacemaker current I, in "ischemic" sheep cardiac Purkinje fibers. Methods By using two microelectrodes voltage clamp technique, to observe the amplitude of I, current in sheep cardiac Purkinje fibers after perfusion with normal Tyrode solution ., 10^-6 -10^-4 mol/L Ado, and ischemia-mimic solution 10^-6 - 10^-4 mol/L Ado at membrane potential levels between - 70 -120mV. Results After perfusion with 10 ^-6 - 10^-4 mol/L Ado in normal Tyrode solution for 15 and 30min, the amplitude of If current was decreased and depended on Ado concentration （n = 10, P < 0. 05 0. 01） , with a result of shifting activation curve of If to a more hyperpolarizing level, but the activation time to a steady-state value was not changed. After perfusion with "ischemia" solution for 15 and 30 min, the amplitude of If current was decreased at all membrane potential levels （ n = 10, P < 0. 05 0. 01） , the activation time reaching a steady state value was prolonged （ ra = 10 , P < 0. 05 ）, with a result of shifting activation curve of I, to a more hyperpolarizing level. When 10 ^-6 - 10^-4 mol/L Ado was added to the solution after 30min "ischemia" , the amplitude of If decreased significantly at all measured membrane potentials and continued further more for another 15 and 30min （n =10, P <0. 05 - 0. 01）. Conclusion This suggests that ischemia metabolite-Ado may have an inhibitory effect on the normal pacemaker activity of the ventricle. "Ischemia" condition could aggravate the suppression by different concentration Ado.更多还原