Lasunción M A, Herrera E
Horm Metab Res. 1981 Jun;13(6):335-9. doi: 10.1055/s-2007-1019260.
Triglyceride-rich lipoproteins (chylomicrons and very low density lipoproteins) were labelled "in vivo" by injecting (U-14C)-glycerol and (9-10(n)-3H)-palmitate in female rats. After purification, these lipoproteins contained most of the 3H in esterified fatty acids and the 14C in glyceride glycerol of neutral lipids. This preparation was incubated "in vitro" in the presence of either isolated adipocytes or epididymal fat pad pieces from male rats. With the incubation, a certain proportion of both 3H-esterified fatty acids and 14C-glyceride glycerol disappeared from the medium, the effect being greater when the incubations were performed with adipocytes than with fat pad pieces. Much greater radioactivity appeared in the lipids of adipocytes than in those of fat pad pieces at the end of 60 or 120 min incubation, and the incorporation of 3H being relatively greater than that of 14C. With the latter isotope, the label appeared not only in the glyceride glycerol fraction but also in the free and esterified fatty acids. Although it is known that lipoproteins lipase activity is lower in adipocytes than in fat pad pieces, our results indicate that, in the former preparation, the enzyme may be more accessible for the substrate. These data also demonstrate that glycerol released by the hydrolysis of lipoprotein glycerides may be partially incorporated into lipids by adipose tissue.
通过向雌性大鼠注射（U - 14C）甘油和（9 - 10(n) - 3H）棕榈酸，对富含甘油三酯的脂蛋白（乳糜微粒和极低密度脂蛋白）进行“体内”标记。纯化后，这些脂蛋白的中性脂质中，大部分3H存在于酯化脂肪酸中，14C存在于甘油酯甘油中。将该制剂在来自雄性大鼠的分离脂肪细胞或附睾脂肪垫片存在的情况下进行“体外”孵育。随着孵育进行，培养基中一定比例的3H - 酯化脂肪酸和14C - 甘油酯甘油消失，与脂肪垫片相比，用脂肪细胞进行孵育时这种效果更明显。在孵育60或120分钟结束时，脂肪细胞脂质中的放射性比脂肪垫片中的放射性高得多，并且3H的掺入相对比14C的掺入更大。对于后一种同位素，标记不仅出现在甘油酯甘油部分，还出现在游离脂肪酸和酯化脂肪酸中。尽管已知脂肪细胞中的脂蛋白脂肪酶活性低于脂肪垫片，但我们的结果表明，在前一种制剂中，该酶对底物可能更容易接近。这些数据还表明，脂蛋白甘油酯水解释放的甘油可能部分被脂肪组织掺入脂质中。
