Werner J C, Sicard R E, Schuler H G
Department of Pediatrics, Rhode Island Hospital, Brown University, Providence 02903.
Am J Physiol. 1989 Feb;256(2 Pt 1):E315-21. doi: 10.1152/ajpendo.1989.256.2.E315.
Palmitate oxidation and the effect of palmitate on glucose and lactate utilization were investigated in isolated, perfused, fetal (0.9 gestation), and neonatal (2 day old) pig hearts. Hearts were perfused under working conditions, developing a mean aortic pressure of 50-55 mmHg, paced at 180 beats/min for 30 min, with Krebs-Henseleit buffer containing 3% albumin, glucose (5 mM), and insulin (100 microU/ml). Palmitate (1 mM) and lactate (5 mM), either individually or in combination, were added to the perfusion buffer. Palmitate oxidation was assessed from 14CO2 production from [U-14C]-palmitate, glucose uptake as 3H2O production from D-[2-3H]-glucose, and lactate metabolism from changes in buffer lactate content. After perfusion, ATP, creatine phosphate, triglycerides, and glycogen were measured. Substantial palmitate oxidation was observed at both ages but was greater in neonatal hearts. Nevertheless, palmitate inhibited lactate utilization and glucose uptake similarly in fetal and neonatal hearts. Lactate also reduced palmitate uptake and oxidation by 40-60% in both fetal and neonatal hearts. During perfusions with palmitate, tissue concentrations of triglycerides increased approximately threefold in fetal hearts and were unaffected by lactate. Thus both palmitate and lactate can act as major energy substrates for the immature heart. Both substrates significantly (P less than 0.01) suppress glucose utilization, and each has suppressive effects on the other's metabolism.
在离体灌注的胎儿（妊娠0.9期）和新生（2日龄）猪心脏中，研究了棕榈酸氧化以及棕榈酸对葡萄糖和乳酸利用的影响。心脏在工作条件下进行灌注，平均主动脉压维持在50 - 55 mmHg，以180次/分钟的频率起搏30分钟，灌注液为含有3%白蛋白、葡萄糖（5 mM）和胰岛素（100微单位/毫升）的 Krebs - Henseleit 缓冲液。将棕榈酸（1 mM）和乳酸（5 mM）单独或联合添加到灌注缓冲液中。通过[U - 14C] - 棕榈酸产生的14CO2评估棕榈酸氧化，通过D - [2 - 3H] - 葡萄糖产生的3H2O评估葡萄糖摄取，并根据缓冲液中乳酸含量的变化评估乳酸代谢。灌注后，测量ATP、磷酸肌酸、甘油三酯和糖原。在两个年龄段的心脏中均观察到大量的棕榈酸氧化，且新生心脏中的氧化量更大。然而，棕榈酸在胎儿和新生心脏中对乳酸利用和葡萄糖摄取的抑制作用相似。在胎儿和新生心脏中，乳酸也使棕榈酸摄取和氧化减少40 - 60%。在用棕榈酸灌注期间，胎儿心脏中甘油三酯的组织浓度增加了约三倍，且不受乳酸影响。因此，棕榈酸和乳酸均可作为未成熟心脏的主要能量底物。两种底物均显著（P < 0.01）抑制葡萄糖利用，且彼此对对方的代谢均有抑制作用。
