Tulenko T N, Rabinowitz J L
Am J Physiol. 1981 Jan;240(1):E65-71. doi: 10.1152/ajpendo.1981.240.1.E65.
The utilization of exogenous acetate and palmitate for the synthesis of vascular wall lipids was studied in isolated blood vessels of the human placenta under high- and low-oxygen conditions. Arteries and veins were obtained from fresh placental material and incubated in Krebs-Henseleit buffer (pH 7.4 at 37 degrees C) containing (in mM) either [2-14C]acetate, 0.11; [1-14C]palmitate, 0.43; or [16-14C]palmitate, 0.43. At the end of the 180-min incubation, neutral lipids accounted for 40%, and phospholipids 60%, of the 14C recovered. Following incubation with either precursor, 14C label was recovered mainly in 16-carbon fatty acids (FA) (35%) and 18-carbon FA (45%); less than 10% was recovered in less than or equal to 14-carbon FA and greater than or equal to 20-carbon FA. Estimates of synthesis rate however indicated that the 18- and 20-carbon FA had the highest turnover rates. Schmidt degradation analysis demonstrated considerable labeling of alkyl carbons after incubation with either carboxyl- or alkyl-labeled precursors, indicating that FA degradation products were used for de novo FA synthesis. Collectively, these findings suggest the presence of both de novo and chain elongation pathways. No differences were observed between arteries and veins, and anoxia had little influence on FA metabolism. Analysis of ATP levels demonstrated elevated concentrations of ATP present, accounting for the apparent lack of anoxic inhibition of FA metabolism.
在高氧和低氧条件下，对人胎盘离体血管中外源乙酸盐和棕榈酸盐用于合成血管壁脂质的情况进行了研究。从新鲜胎盘组织中获取动脉和静脉，并在含有（以毫摩尔计）[2-¹⁴C]乙酸盐（0.11）、[1-¹⁴C]棕榈酸盐（0.43）或[16-¹⁴C]棕榈酸盐（0.43）的Krebs-Henseleit缓冲液（37℃时pH 7.4）中孵育。在180分钟孵育结束时，回收的¹⁴C中，中性脂质占40%，磷脂占60%。在用任何一种前体孵育后，¹⁴C标记主要在16碳脂肪酸（FA）（35%）和18碳FA（45%）中回收；在小于或等于14碳FA和大于或等于20碳FA中的回收量不到10%。然而，合成速率估计表明，18碳和20碳FA的周转率最高。施密特降解分析表明，在用羧基标记或烷基标记的前体孵育后，烷基碳有相当程度的标记，这表明FA降解产物被用于从头合成FA。总的来说，这些发现表明存在从头合成途径和链延长途径。在动脉和静脉之间未观察到差异，缺氧对FA代谢影响很小。ATP水平分析表明存在升高的ATP浓度，这解释了FA代谢明显缺乏缺氧抑制的原因。
