心肌氨基酸代谢与早期急性心肌缺血的关系

作者结扎家兔左冠状动脉前降支,对急性心肌缺血时蛋白质的降解和氨基酸代谢进行了研究。用离子交换色谱法测定缺血心肌组织游离氨基酸(酸性、中性、碱性)以及氨含量,发现缺血时大多数游离氨基酸含量上升,丙氨酸、缬氨酸、异亮氨酸和组氨酸含量在缺血15min即有明显增加,但苏氨酸、谷氨酸和游离氨基酸总量却随缺血时间的延长而逐渐下降。丝氨酸含量在缺血早期上升,缺血60～480min,含量无明显变化。缺血120min以后,甘氨酸和精氨酸含量逐渐下降。组织氨含量在缺血早期上升,晚期下降。游离氨基酸总量、苏氨酸、甘氨酸、精氨酸以及组织氨含量的降低是缺血心肌氨基酸代谢的特征性变化。作者认为:测定缺血心肌游离氨基酸及组织氨含量有助于急性心肌缺血的早期诊断。

RELATIONSHIP BETWEEN AMINO ACID METABOLISM AND EARLY ACUTE MYOCARDIAL ISCHEMIA

Degradation of protein and amino acid metabolism were studied in acute ischemic myocardium of rabbit whose anterior descending branch of the left coronary artery(LAD) was ligated. Free acidic, neutral and basic amino acids and ammonia in ischemic myocardium were determined by ion exchange chromatography, It was found that most of free amino acids increased in the course of ischemia. Sigificant increase of alanine, valine, isoleucine and histidine was noted at 15 min of ischemia. With the prologation of the ischemia, the content of threonine and glutamic acid and the total amount of free amino acids decreased progressively, The fcontent of serine increased in early period of ischemia, While no significant change was found during 60～480 min of ischemia. There was a decrease in glycine and arginine content 120 min after ischemia. The ammonia concentration increased in early period of ischemia, but decreased in late time, In early ischemia myocardium protein degradation is accelerated and amino acid metabolism is different from those in autolyaing myocardium. It is suggested that the decrease of the total amount of the free amino acids, and threonine, glycine, arginine as well as the content of the ammonia is the characteristic change of the amino acid metabolism in ischemic myocardium which is helpful for the early diagnosis of acute myocardial ischemia.