Ilangovan Govindasamy, Liebgott Thibaut, Kutala Vijay Kumar, Petryakov Sergey, Zweier Jay L, Kuppusamy Periannan
Department of Internal Medicine, The Ohio State University, Columbus, Ohio, USA.
Magn Reson Med. 2004 Apr;51(4):835-42. doi: 10.1002/mrm.20000.
Oxygen plays a critical role in the pathophysiology of myocardial injury during both ischemia and subsequent reperfusion (I/R). Thus, oxygen concentration is an important variable to measure during I/R. In the present work, electron paramagnetic resonance (EPR)-based oximetry was used to measure the oxygen concentration during a series of I/R episodes and oxygenation levels were correlated with the contractile and hemodynamic functions of the heart. A custom-developed electronically tunable surface coil resonator working at 1.1 GHz was used to determine tissue pO(2) in the beating heart. Microcrystalline particulate of lithium phthalocyanine was used as an EPR oximetry probe. Isolated and perfused rat hearts were subjected to 1 or 3 hr durations of preischemic perfusion, followed by 15-min I/R cycles. In hearts perfused for 3 hr prior to 15-min I/R cycles, the myocardial pO(2) decreased gradually on subsequent reperfusions of three successive I/R cycles. However, in hearts perfused for 1 hr there was almost 100% recovery of myocardial pO(2) in all three I/R cycles. The extent of oxygenation recovered in each reperfusion cycle correlated with the recovery of hemodynamic and contractile function. The results also showed that the oxygen consumption rate of the heart at the end of each I/R episode decreased in direct proportion to the functional recovery. In summary, it was observed that the amount of myocardial oxygen consumption during I/R could provide a reliable index of functional impairment in the heart.
在缺血及随后的再灌注（I/R）过程中，氧在心肌损伤的病理生理学中起着关键作用。因此，氧浓度是I/R期间需要测量的一个重要变量。在本研究中，基于电子顺磁共振（EPR）的血氧测定法被用于测量一系列I/R过程中的氧浓度，并且氧合水平与心脏的收缩和血流动力学功能相关。一个定制开发的工作在1.1 GHz的电子可调表面线圈谐振器被用于测定跳动心脏中的组织pO₂。酞菁锂微晶颗粒被用作EPR血氧测定探针。分离并灌注的大鼠心脏先进行1或3小时的缺血前灌注，然后进行15分钟的I/R循环。在进行15分钟I/R循环前灌注3小时的心脏中，在随后连续三个I/R循环的再灌注过程中，心肌pO₂逐渐下降。然而，在灌注1小时的心脏中，在所有三个I/R循环中几乎有100%的心肌pO₂恢复。每个再灌注循环中氧合恢复的程度与血流动力学和收缩功能的恢复相关。结果还表明，每个I/R过程结束时心脏的氧消耗率与功能恢复成反比下降。总之，观察到I/R期间心肌氧消耗的量可以提供心脏功能损害的可靠指标。
