METABOLISM OF ACETATE AND GLUCOSE BY ISOLATED PERFUSED UDDER .2. CONTRIBUTION OF ACETATE AND GLUCOSE TO CARBON DIOXIDE AND MILK CONSTITUENTS
METABOLISM OF ACETATE AND GLUCOSE BY ISOLATED PERFUSED UDDER .2. CONTRIBUTION OF ACETATE AND GLUCOSE TO CARBON DIOXIDE AND MILK CONSTITUENTS
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DOI：
10.1042/bj0880213
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发表时间：
1963-01-01
影响因子：
4.1
通讯作者：
LINZELL, JL
中科院分区：
文献类型：
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作者：
HARDWICK, DC;MEPHAM, TB;LINZELL, JL
将含有均匀标记的[Cl_4]葡萄糖（[U-Cl_4]葡萄糖）或[2-C_（14）]-乙酸盐的葡萄糖、乙酸盐和氨基酸的底物混合物输注到4个离体灌注的泌乳山羊乳腺的灌注液中6-9小时。在使用[U-Cl 4]葡萄糖的实验中，77%的牛奶乳糖、23%的牛奶甘油三酯甘油、41%的牛奶柠檬酸盐、0.5%的牛奶甘油三酯脂肪酸和39%的呼出CO2来自添加的葡萄糖。在另一项使用[2-C14]乙酸盐的实验中，只有0.3%的牛奶乳糖、2%的牛奶甘油三酯甘油和14%的呼出CO2来自添加的乙酸盐。然而，48%的牛奶甘油三酯脂肪酸，90%的挥发性脂肪酸和约33%的牛奶柠檬酸盐来自这种前体。[2-C14]乙酸盐标记牛奶脂肪酸，但[U-C14]-葡萄糖不标记牛奶脂肪酸，这与两者对牛奶柠檬酸盐的相同标记形成对比。两个乙酰辅酶A池和丙酮酸羧化的可能性进行了讨论。与乳糖相比，牛奶甘油和脂肪酸的比放射性最初缓慢上升，表明甘油三酯和前体的储存量大于乳糖和前体。
A substrate mixture of glucose, acetate and amino acids containing either uniformly labelled [Cl4]glucose ([U-Cl4]glucose) or [2-C14]-acetate was infused for 6-9 hours into the perfusion fluid of 4 isolated perfused mammary glands of lactating goats. In an experiment with [U-Cl4]glucose, 77% of the milk lactose, 23% of milk triglyceride glycerol, 41% of milk citrate, 0.5% of milk triglyceride fatty acids and 39% of the expired CO2 came from added glucose. In another experiment with [2-C14]acetate, only 0.3% of the milk lactose, 2% of milk triglyceride glycerol and 14% of expired CO2 came from added acetate. However, 48% of the milk triglyceride fatty acids, 90% of the volatile fatty acids and about 33% of the milk citrate came from this precursor. The labelling of milk fatty acids by [2-C14]acetate but not by [U-C14]-glucose is contrasted with the equal labelling of milk citrate by both. The possibilities of two acetyl-CoA pools and of the carboxylation of pyruvate are discussed. The slow initial rise in the specific radioactivities of both milk glycerol and fatty acids, as compared with that of lactose, suggests the existence of larger stores of triglyceride and precursors than of lactose and precursors.