Stender S, Zilversmit D B
Biochim Biophys Acta. 1981 Mar 23;663(3):674-86. doi: 10.1016/0005-2760(81)90079-5.
The influx of free and esterified cholesterol into various tissues of cholesterol-fed rabbits is calculated from the tissue [3H] cholesterol and [14C] cholesterol content - corrected for radioactivity in contaminating plasma - after a 3--6 h exposure to in vivo-labeled plasma. The plasma free cholesterol was labeled primarily with 3H and the esterified cholesterol with 14C or vice versa. The influx calculation is based on total 3H and 14C in tissues and two linear equations that take into account esterification and hydrolysis of sterol fractions by the tissues. The influx of esterified cholesterol into tissue samples from aorta, heart, small intestine and lung was 10--80 nmol-g--1-h--1, whereas the influx into adrenal, spleen and liver was from 400--2500 nmol--g-1--h-1. The influx of free cholesterol was considerably higher than expected if free and esterified cholesterol had entered the tissues together as part of plasma lipoproteins. This excess of free cholesterol influx can be ascribed to cholesterol exchange between plasma lipoproteins and tissues, which in several tissues amounted to more than 80% of the total free cholesterol influx. From tissue free and esterified cholesterol radioactivity, one can calculate that 20--70% of the newly entered esterified cholesterol was hydrolyzed by various tissues and that most tissues esterified less than 10% of newly entered cholesterol during the experimental period. However, esterification of plasma cholesterol by adrenals averaged 50% of that taken up during a 3-6 h period.
在给胆固醇喂养的兔子体内标记血浆3 - 6小时后，根据组织中[3H]胆固醇和[14C]胆固醇含量（校正了污染血浆中的放射性）来计算游离胆固醇和酯化胆固醇进入兔子各组织的量。血浆游离胆固醇主要用3H标记，酯化胆固醇用14C标记，反之亦然。流入量的计算基于组织中总的3H和14C以及两个线性方程，这两个方程考虑了组织中甾醇部分的酯化和水解情况。酯化胆固醇流入主动脉、心脏、小肠和肺组织样本的量为10 - 80 nmol·g-1·h-1，而流入肾上腺、脾脏和肝脏的量为400 - 2500 nmol·g-1·h-1。如果游离胆固醇和酯化胆固醇作为血浆脂蛋白的一部分一起进入组织，那么游离胆固醇的流入量会比预期高得多。这种游离胆固醇流入量的过量可归因于血浆脂蛋白与组织之间的胆固醇交换，在几个组织中，这种交换量占游离胆固醇总流入量的80%以上。根据组织中游离胆固醇和酯化胆固醇的放射性，可以计算出，新进入的酯化胆固醇有20 - 70%被各种组织水解，并且在实验期间，大多数组织酯化的新进入胆固醇不到10%。然而，肾上腺对血浆胆固醇的酯化平均占3 - 6小时内摄取量的50%。
