HEPATIC TRIGLYCERIDE HYDROLYSIS AND DEVELOPMENT OF KETOGENESIS IN RABBITS
HEPATIC TRIGLYCERIDE HYDROLYSIS AND DEVELOPMENT OF KETOGENESIS IN RABBITS
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DOI：
10.1152/ajpendo.1985.249.5.e478
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发表时间：
1985-01-01
影响因子：
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通讯作者：
GIRARD, J
中科院分区：
文献类型：
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作者：
DUEE, PH;PEGORIER, JP;GIRARD, J
内源性脂肪酸或外源性油酸加肉碱在胎兔、新生兔和70日龄兔的分离肝细胞中发生酮的研究。在出生后的第一个48小时内，肝脏的三酰甘油储存量减少了80%。用溶酶体酸性脂肪酶抑制剂和溶酶促进剂在24小时龄禁食兔肝细胞中研究了肝三酰甘油储备物的水解性。它们的加入使酮体生成率降低了60%-70%，这表明肝脏三酰甘油的水解是通过位于溶酶体中的酸性脂肪酶进行的。然而，在胎兔肝细胞中，内源性外源脂肪酸的生酮能力很低，而在出生后6-24小时内，内源性外源脂肪酸的生酮能力增加了8倍，而且三酰甘油储存的水解物足以支持24小时龄兔肝细胞的生酮能力。新生兔肝细胞中酮生成的出现是由出生相关因素触发的，而不是精确到胎儿成熟的阶段。脂肪酸主要在线粒体中被氧化，因为过氧化物酶的氧化不超过整个β-氧化的10-15%。分离的肝细胞与[1-14C]油酸孵育后，在出生时，脂肪酸优先进入酯化(93%的油酸代谢)，而不是进入氧化。相反，油酸氧化占出生后24小时代谢的油酸总量的50%。讨论了油酸在出生后第1天进入酯化和氧化的过程中所涉及的因素。
Kefogenesis from endogenous fatty acids or exogenous oleate plus carnitine has been studied in isolated hepatocytes from fetal, newborn, and 70-day-old rabbits. During the first 48 h after birth, hepatic triacylglycerol stores decrease by 80%. The hydrolysis of hepatic triacylglycerol stores has been studied in isolated hepatocytes from 24-h-old fasting rabbits by using lysosomal acid lipase inhibitors and lysosomotropic agents. Their addition decreases the rates of ketone body production by 60-70%, suggesting that the hepatic triacylglycerol hydrolysis proceeds via an acid lipase located in the lysosomes. Whereas the rates of ketogenesis from endogenous of exogenous fatty acids are very low in isolated hepatocytes from fetal rabbit, an eightfold increase in the rate of ketogenesis occurs between 6 and 24 h after birth; furthermore the hydrolysis of triacylglycerol stores is sufficient to support the ketogenic capacity in the hepatocytes isolated from 24-h-old rabbits. The emergence of ketogenesis in newborn rabbit hepatocytes is triggered by birth-associated factors rather than to an accurate stage of fetal maturation. Fatty acids are mainly oxidized in the mitochondria because peroxisomal oxidation does not exceed 10-15% of the overall .beta.-oxidation. Isolated hepatocytes incubated with [1-14C]oleate exhibit at birth a preferential channeling of fatty acid into esterification (93% of oleate metabolized) rather than into oxidation. Conversely oleate oxidation represents 50% of total oleate metabolized 24 h after birth. Factors involved in this switch on of the partition of oleate into esterification and oxidation during the 1st day after birth are discussed.