McCarthy R D, Coccodrilli G D
J Dairy Sci. 1975 Feb;58(2):164-8. doi: 10.3168/jds.S0022-0302(75)84539-5.
Intravenous injection of heparin increases lipoprotein lipase activity of circulating serum presumably by removing the enzyme from its location on the capillary endothelium. The incorporation of carbon-14 uniformly labeled glucose and carbon-14 1-labeled palmitic acid into fractionated milk fat triglycerides was studied in both normal and heparin treated lactating goats. The objective was to remove lipoprotein lipase from the mammary gland capillaries and to contrast normal milk fat synthesis with a situation presumed to cause the gland to be solely dependent on the phosphatidic acid pathway. The studies with labeled glucose indicated that under normal conditions there are two sources of milk glyceride glycerol; while following heparin injections, there is a single glycerol pool providing most of the glyceride glycerol. The investigations with labeled palmitic acid indicated that under normal conditions there are two sources of palmitic acid coming from the blood which enter nonequilibrating cellular pools. Palmitic acid from both pools is available for triglyceride synthesis. Following heparin injections there appears to be a common intracellular pool of pre-formed palmitic acid derived from the blood. The data indicate that lipoprotein lipase operating on blood triglycerides yields a 2-mono-glyceride which subsequently enters the gland and is utilized for milk fat synthesis.
静脉注射肝素可能通过将脂蛋白脂肪酶从其在毛细血管内皮的位置移除，从而增加循环血清中的脂蛋白脂肪酶活性。在正常和经肝素处理的泌乳山羊中，研究了将碳 -14 均匀标记的葡萄糖和碳 -14 1-标记的棕榈酸掺入分级乳脂肪甘油三酯的情况。目的是从乳腺毛细血管中去除脂蛋白脂肪酶，并将正常乳脂肪合成与假定导致腺体仅依赖磷脂酸途径的情况进行对比。用标记葡萄糖进行的研究表明，在正常情况下，乳甘油酯甘油有两个来源；而在注射肝素后，有一个单一的甘油池提供了大部分甘油酯甘油。用标记棕榈酸进行的研究表明，在正常情况下，来自血液的棕榈酸有两个来源，它们进入非平衡的细胞池。两个池中的棕榈酸都可用于甘油三酯合成。注射肝素后，似乎有一个来自血液的预先形成的棕榈酸的共同细胞内池。数据表明，作用于血液甘油三酯的脂蛋白脂肪酶产生一种 2-单甘油酯，其随后进入腺体并用于乳脂肪合成。
