Svedjeholm R, Ekroth R, Joachimsson P O, Ronquist G, Svensson S, Tydén H
Department of Thoracic and Cardiovascular Surgery, Regionsjukhuset, Linköping University, Sweden.
J Thorac Cardiovasc Surg. 1991 Apr;101(4):688-94.
Myocardial metabolism seems to be markedly abnormal during the first hours of reperfusion after aortic crossclamping. Thus we previously demonstrated no uptake of carbohydrate or lipid substrates 1 hour after coronary operations. Amino acids were the only exogenous substrates taken up by the heart. The aim of the present study was to examine if this metabolic abnormality persisted a few hours later. This was done by measuring coronary sinus blood flow and arterial-coronary sinus differences of oxygen, glucose, free fatty acids, glycerol, lactate, beta-OH-butyrate, and amino acids in a similar group of 19 patients 4 to 5 hours after coronary operations. The results demonstrate a change toward normalization of myocardial free fatty acid use, although the threshold for free fatty acid uptake seemed elevated in comparison with that in the normal postabsorptive state. No correlation was found between free fatty acid uptake and myocardial oxygen consumption. Despite elevated arterial levels of glucose, lactate, pyruvate, and beta-OH-butyrate, no uptake was observed. Myocardial amino acid exchange demonstrated a pattern suggestive of postischemic metabolic adaptation. Several amino acids were extracted, glutamate and branched chain amino acids being the quantitatively most important. The uptake of glutamate and branched chain amino acids correlated with myocardial oxygen consumption, which suggests a direct link to myocardial energy metabolism. Myocardial glutamate uptake seemed to be limited by substrate availability.
在主动脉交叉钳夹后的再灌注最初数小时内，心肌代谢似乎明显异常。因此，我们之前证明，冠状动脉手术后1小时，心脏未摄取碳水化合物或脂质底物。氨基酸是心脏摄取的唯一外源性底物。本研究的目的是检验这种代谢异常在数小时后是否仍然存在。我们通过测量19例类似患者冠状动脉手术后4至5小时的冠状窦血流量以及氧、葡萄糖、游离脂肪酸、甘油、乳酸、β-羟基丁酸和氨基酸的动静脉冠状窦差值来进行研究。结果表明，心肌游离脂肪酸利用趋向正常化，尽管与正常吸收后状态相比，游离脂肪酸摄取阈值似乎有所升高。未发现游离脂肪酸摄取与心肌氧消耗之间存在相关性。尽管动脉血中葡萄糖、乳酸、丙酮酸和β-羟基丁酸水平升高，但未观察到摄取现象。心肌氨基酸交换呈现出一种提示缺血后代谢适应的模式。几种氨基酸被摄取，其中谷氨酸和支链氨基酸在数量上最为重要。谷氨酸和支链氨基酸的摄取与心肌氧消耗相关，这表明与心肌能量代谢存在直接联系。心肌谷氨酸摄取似乎受底物可用性的限制。
