Edlund A, Wennmalm A
Acta Physiol Scand. 1981 Sep;113(1):117-22. doi: 10.1111/j.1748-1716.1981.tb06870.x.
Isolated rabbit hearts were perfused according to Langendorff at a temperature of 38 degrees C and a pressure of 5.9 kPa with gassed Tyrode solution. Gas mixtures containing 5% CO2 and 15, 20, 30, 60, or 95% O2 in N2 were used to saturate the perfusion medium. In some cases lactate (50 or 500 microM) was present in the medium perfusing the heart. Coronary flow (CF), oxygen pressure in the perfusion medium and in the cardiac effluent and lactate in the effluent were analysed in all experiments. The oxygen uptake in the hearts perfused with a medium equilibrated at atmospheric pressure with 95% O2 and 5% CO2 (oxygen pressure approximately 87 kPa, oxygen content 19 ml X 1(-1)), averaged 3 ml X 100 g w.w. -1 X min-1. Reduction of the oxygen pressure in the perfusion medium resulted in an increase in CF and in the fractional extraction of oxygen from the medium, making it possible to maintain the heart's oxygen uptake (VO2) down to an oxygen pressure in the perfusion medium of about 24 kPa (oxygen content approximately 5 ml X 1(-1), the perfusion medium equilibrated with 20% O2 and 5% CO2 in N2). Myocardial lactate production was low during perfusion at pO2 approximately 87 kPa but increased rapidly when the oxygen pressure was lowered. The addition of lactate (500 microM) to the perfusion medium at pO2 approximately 87 kP induced a fractional uptake of about 20%. It is concluded that the VO2 observed during perfusion at pO2 approximately 87 kPa mainly reflects aerobic myocardial metabolism in this preparation. This assumption is based on the facts that coronary flow and fractional oxygen extraction are submaximal and that a considerable uptake of lactate occurs concurrently with a very limited production. However, even moderate reduction of the oxygen pressure in the perfusion medium (to approximately 61 kPa) is followed by a significant increase in lactate production, indicating that myocardial oxygenation is inefficient.
将离体兔心按照Langendorff法在38℃、5.9 kPa压力下用充氧的台氏液进行灌注。使用含5%二氧化碳以及氮气中15%、20%、30%、60%或95%氧气的混合气体来使灌注液饱和。在某些情况下，灌注心脏的液体中含有乳酸（50或500微摩尔）。在所有实验中均分析了冠脉流量（CF）、灌注液及心脏流出液中的氧分压以及流出液中的乳酸。用在大气压下与95%氧气和5%二氧化碳平衡的液体灌注的心脏（氧分压约87 kPa，氧含量19毫升×升⁻¹），其氧摄取平均为3毫升×100克湿重⁻¹×分钟⁻¹。灌注液中氧分压的降低导致冠脉流量增加以及从灌注液中氧的分数提取增加，从而能够将心脏的氧摄取（VO₂）维持至灌注液中氧分压约24 kPa（氧含量约5毫升×升⁻¹，灌注液在氮气中与20%氧气和5%二氧化碳平衡）。在氧分压约87 kPa灌注期间心肌乳酸生成较低，但当氧分压降低时迅速增加。在氧分压约87 kPa时向灌注液中添加乳酸（500微摩尔）会引起约二十%的分数摄取。得出的结论是，在氧分压约87 kPa灌注期间观察到的VO₂主要反映了该制剂中的有氧心肌代谢。这一假设基于以下事实：冠脉流量和氧的分数提取未达到最大值，并且在乳酸生成非常有限的同时发生了相当量的乳酸摄取。然而，即使灌注液中氧分压适度降低（至约61 kPa），随后乳酸生成也会显著增加，表明心肌氧合效率低下。
