Tosaki A, Hearse D J
Am J Physiol. 1987 Aug;253(2 Pt 2):H225-33. doi: 10.1152/ajpheart.1987.253.2.H225.
By using the isolated rat heart with regional ischemia and a perfusate Ca2+ of 2.4 mM, we have observed a bell-shaped relationship between the incidence of reperfusion-induced ventricular fibrillation (VF) and the duration of preceding ischemia. With 5, 10, 20, 30, and 40 min of ischemia, 8, 83, 58, 25, and 8% of the hearts (n = 12 per group) exhibited irreversible VF. In additional studies (10 min ischemia) perfusate Ca2+ was reduced (to 0.1, 0.4, 0.8, 1.2, 1.6, and 2.0 mM) for 1 min before coronary occlusion (to trap low Ca2+ in the ischemic zone) and for 1 min before and throughout reperfusion. VF fell in a dose-dependent manner from its control incidence of 83% (2.4 mM Ca2+) to 17 (P less than 0.01), 25 (P less than 0.01), 41, 58, 91, and 83%, respectively. In further studies Ca2+ was reduced to 0.4 mM just before ischemia and also just before and during reperfusion, and the ischemic time was varied (5, 10, 20, 30, or 40 min), VF was reduced from its time-matched control (2.4 mM Ca2+) values of 8, 83, 58, 25, and 8% to 0, 25 (P less than 0.01), 8 (P less than 0.05), 0, and 0%, respectively. In a final series of experiments, Ca2+ reduction (to 0.4 mM) was carried out only during reperfusion (1 min before and throughout reperfusion). When time-vulnerability curves were constructed some protection was observed after 20 min of ischemia (VF fell from its control incidence of 58 to 8%). We conclude that extracellular Ca2+ concentration can influence vulnerability to reperfusion-induced arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)
通过使用局部缺血的离体大鼠心脏以及灌注液中钙离子浓度为2.4 mM的条件，我们观察到再灌注诱导的心室颤动（VF）发生率与先前缺血持续时间之间呈钟形关系。缺血5、10、20、30和40分钟时，心脏（每组n = 12）发生不可逆VF的比例分别为8%、83%、58%、25%和8%。在另外的研究中（缺血10分钟），在冠状动脉闭塞前1分钟（以在缺血区捕获低钙离子浓度）以及再灌注前和再灌注全程1分钟，将灌注液钙离子浓度降低（至0.1、0.4、0.8、1.2、1.6和2.0 mM）。VF以剂量依赖方式从其对照发生率83%（2.4 mM钙离子）分别降至17%（P < 0.01）、25%（P < 0.01）、41%、58%、91%和83%。在进一步研究中，就在缺血前以及再灌注前和再灌注期间将钙离子浓度降至0.4 mM，并改变缺血时间（5、10、20、30或40分钟），VF从其时间匹配对照（2.4 mM钙离子）值8%、83%、58%、25%和8%分别降至0%、25%（P < 0.01）、8%（P < 0.05）、0%和0%。在最后一系列实验中，仅在再灌注期间（再灌注前1分钟和再灌注全程）进行钙离子浓度降低（至0.4 mM）。构建时间易损性曲线时，缺血20分钟后观察到了一定程度的保护作用（VF从其对照发生率58%降至8%）。我们得出结论，细胞外钙离子浓度可影响对再灌注诱导心律失常的易感性。（摘要截短至250字）
