Ascuitto R J, Ross-Ascuitto N T, Chen V, Downing S E
Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06510.
Am J Physiol. 1989 Jan;256(1 Pt 2):H9-15. doi: 10.1152/ajpheart.1989.256.1.H9.
Studies in which subcellular systems were used suggest that neonatal myocardium has a sharply limited capacity to metabolize fatty acids. The relationship of these findings to the intact heart was tested on piglets, 8 h to 12 days of age. Left ventricular (LV) performance, O2 consumption (MVO2), and fatty acid (FA) uptake and oxidation were measured. Hearts were perfused at 70 cmH2O pressure with buffer containing 2% bovine serum albumin, insulin (100 microU/ml), 5 mM glucose, and 1.5 mM lactate. 14C-labeled palmitate was added (net FA, 0.5 mM). Washed erythrocytes were used to assure adequate O2 delivery. LV end-diastolic pressure (EDP) was controlled with a fluid-filled balloon. FA oxidation was estimated by measuring 14CO2 production. Hearts less than 24 h (group I, n = 6), those approximately 3 days (group II, n = 5), and those 6-12 days of age (group III, n = 10) were compared. Measurements at a low EDP (2-4 cmH2O) and at a higher EDP (7-9 cmH2O) were compared. At the low EDP, rates of FA oxidation for groups I-III averaged 30.0 +/- 3.0, 31.4 +/- 2.9, and 50.2 +/- 2.6 nmol.min-1.g-1, respectively. These values increased to 43.8 +/- 3.7, 42.6 +/- 2.5, and 63.8 +/- 4.0 nmol.min-1.g-1, respectively, at the higher EDP level (P less than 0.01 for each group). Thus within a few hours of birth, pig hearts are able to oxidize long-chain FA, and the rate of oxidation is linked to mechanical function. However, both the oxidation rate and the percentage of MVO2 accounted for by FA oxidation are greater in older hearts.
使用亚细胞系统的研究表明，新生心肌代谢脂肪酸的能力极为有限。在8小时至12日龄的仔猪身上测试了这些发现与完整心脏的关系。测量了左心室（LV）功能、耗氧量（MVO2）以及脂肪酸（FA）摄取和氧化情况。心脏在70 cmH2O压力下用含有2%牛血清白蛋白、胰岛素（100微单位/毫升）、5 mM葡萄糖和1.5 mM乳酸的缓冲液灌注。加入14C标记的棕榈酸（净FA，0.5 mM）。使用洗涤过的红细胞以确保充足的氧气输送。通过充液球囊控制LV舒张末期压力（EDP）。通过测量14CO2生成量来估算FA氧化。比较了小于24小时的心脏（I组，n = 6）、约3天的心脏（II组，n = 5）以及6 - 12岁的心脏（III组，n = 10）。比较了低EDP（2 - 4 cmH2O）和高EDP（7 - 9 cmH2O）时的测量结果。在低EDP时，I - III组的FA氧化速率分别平均为30.0 +/- 3.0、31.4 +/- 2.9和50.2 +/- 2.6 nmol·min-1·g-1。在较高EDP水平时，这些值分别增加到43.8 +/- 3.7、42.6 +/- 2.5和63.8 +/- 4.0 nmol·min-1·g-1（每组P < 0.01）。因此，出生后数小时内，猪心脏就能氧化长链FA，且氧化速率与机械功能相关。然而，老年心脏的氧化速率以及FA氧化占MVO2的百分比都更高。
