Varadarajan Srinivasan G, An Jianzhong, Novalija Enis, Stowe David F
Anesthesiology Research Laboratories, Department of Anesthesiology, The Medical College of Wisconsin, Milwaukee, 53226, USA.
Anesthesiology. 2002 Jan;96(1):125-33. doi: 10.1097/00000542-200201000-00025.
Ca(2+) loading occurs during myocardial reperfusion injury. Volatile anesthetics can reduce reperfusion injury. The authors tested whether sevoflurane administered before index ischemia in isolated hearts reduces myoplasmic diastolic and systolic [Ca(2+)] and improves function more so than when sevoflurane is administered on reperfusion.
Four groups of guinea pig hearts were perfused with crystalloid solution (55 mmHg, 37 degrees C): (1) no treatment before 30 min global ischemia and 60 min reperfusion (CON); (2) 3.5 vol% sevoflurane administered for 10 min before ischemia (SBI); (3) 3.5 vol% sevoflurane administered for 10 min after ischemia (SAI); and (4) 3.5 vol% sevoflurane administered for 10 min before and after ischemia (SBAI). Phasic myoplasmic diastolic and systolic [Ca(2+)] were measured in the left ventricular free wall with the fluorescence probe indo-1.
Ischemia increased diastolic [Ca(2+)] and diastolic left ventricular pressure (LVP). In CON hearts, initial reperfusion greatly increased diastolic [Ca2+] and systolic [Ca(2+)] and reduced contractility (systolic-diastolic LVP, dLVP/dt(max)), relaxation (diastolic LVP, dLVP/dt(min)), myocardial oxygen consumption (MvO(2)), and cardiac efficiency. SBI, SAI, and SBAI each reduced ventricular fibrillation, attenuated increases in systolic and systolic-diastolic [Ca(2+)], improved contractile and relaxation indices, and increased coronary flow, percent oxygen extraction, MvO(2), and cardiac efficiency during 60 min reperfusion compared with CON. SBI was more protective than SAI, and SBAI was generally more protective than SAI.
Sevoflurane improves postischemic cardiac function while reducing Ca(2+) loading when it is administered before or after ischemia, but protection is better when it is administered before ischemia. Reduced Ca(2+) loading on reperfusion is likely a result of the anesthetic protective effect.
心肌再灌注损伤期间会发生钙（Ca²⁺）超载。挥发性麻醉剂可减轻再灌注损伤。作者测试了在离体心脏初次缺血前给予七氟醚是否比在再灌注时给予七氟醚更能降低肌浆舒张期和收缩期的[Ca²⁺]并改善心脏功能。
四组豚鼠心脏用晶体溶液灌注（55 mmHg，37℃）：（1）在30分钟全心缺血和60分钟再灌注前不进行处理（CON）；（2）在缺血前给予3.5%体积分数的七氟醚10分钟（SBI）；（3）在缺血后给予3.5%体积分数 的七氟醚10分钟（SAI）；（4）在缺血前后各给予3.5%体积分数的七氟醚10分钟（SBAI）。用荧光探针indo-1测量左心室游离壁肌浆舒张期和收缩期的[Ca²⁺]。
缺血增加了舒张期[Ca²⁺]和舒张期左心室压力（LVP）。在CON组心脏中，初次再灌注极大地增加了舒张期[Ca²⁺]和收缩期[Ca²⁺]，并降低了收缩性（收缩期-舒张期LVP，dLVP/dt(max)）、舒张性（舒张期LVP，dLVP/dt(min)）、心肌耗氧量（MvO₂）和心脏效率。与CON组相比，SBI、SAI和SBAI均减少了室颤，减轻了收缩期和收缩期-舒张期[Ca²⁺]的升高，改善了收缩和舒张指标，并增加了60分钟再灌注期间的冠脉流量、氧摄取百分比、MvO₂和心脏效率。SBI比SAI的保护作用更强，SBAI总体上比SAI的保护作用更强。
七氟醚在缺血前后给予时可改善缺血后心脏功能，同时减少Ca²⁺超载，但在缺血前给予时保护作用更佳。再灌注时Ca²⁺超载的减少可能是麻醉剂保护作用的结果。
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