【摘要】 目的:观察缺血预处理(IPC)的次数对缺血-再灌流过程中兔心脏电生理活动的影响,探讨IPC的抗心律失常作用机制。方法:家兔24只,随机分为对照组(C)、缺血组(IR)、一次预处理组(SPC)和两次预处理组(BPC)。应用心外膜单相动作电位(MAP)探针记录技术检测缺血-再灌流过程中MAP幅度(MAPA)、复极50%时程(MAPD50)、零相最大上升速度(Vmax)及心律失常发生率。结果:各预处理组中缺血后5min时的MAPD50、MAPA、Vmax迅速缩短或降低(P<0.05)。SPC组与IR组相比,促进了缺血20min之后MAPA、Vmax的恢复,改善了缺血20minMAPD50的过度缩短,限制了复灌时MAPD50的过度延长(P<0.05)。SPC完全抑制了缺血-再灌中室颤的发生率(0%,P<0.05)。BPC组中,缺血-再灌注中室颤发生率及在缺血30min末及再灌注末上述参数与缺血组比较均无显著差异。结论:①SPC在在体家兔心脏上具有最好的抗心律失常作用,随IPC次数增加,其抗心律失常作并不增强;②缺血早期SPC迅速缩短MAPD,抗早期心律失常的机制可能是缩小了造成单向阻滞的窗口;③改善缺血晚期电生理参数,抗晚期心律失常的机制可能是减小不应期离散度;④限制复灌时MAPD过度延长,抗再灌注心律失常可能与减少内向离子流及触发活性有关。更多还原

【Abstract】 Objective:To investigate the effects o f various“doses”of ischemia preconditioning(IPC)on electrophysiological activi ty in acute ischemia heart of rabbit and to approach the possible antiarrhythmic mechanism of IPC.Methods:Twenty-four rabbits were divided into four groups random-ly:control,IR(ischemia-reperfusion),SPC(sin gle ischemia precond itioning)and BPC(bi-ischemia precon-ditioning).With the recording techniqu es of monophasic action potential(MAP),we continually monitored MAP to obers erve the effects of various“dose”of IPC on parameters of MAP such as(50%of dura-tion of MAP)MAPD 50 ,(amplitude of MAP)MAPA,and(the maxium depolarization velocity)Vmax an d the incidence of arrhythmia.the ECG was monitored in experiment.Re sults:At 5min after ischemia com-pared with those of IR group,the MAPD 50 ,MAPA and Vmax in SPC and BPC groups were significant-ly decreased(P<0 .05)and improved at20-min after ischemia in SPC group;in addition.the e xcessive width of MAPD 50 in reperfusion was limited in SPC group(P<0.05).SPC totally suppress ed ventricular fibrillation(P<0.05).The incidence of arrhythmia at the e nd of ischemia in BPC group was similar to those in IR group.Conclusions:①SPC is the best selection to acquire the a ntiarrhthymic effect that has no dose-dependency.②In the early phase of is ch emia SPC promotes shortening of MAPD 50 so as to weaken slow conduction.③In the late phase of ischemia SPC improve s parameters of MAP so as to re-duce the dispersion of(effective refractory pe riod)ERP.④In reperfusion SPC limits the excessive width of MAPD 50 .更多还原