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A rapid method for mass isolation of functionally intact hepatocytes and reticuloendothelial cells from a single rat liver is described. The technique is based on collagenase perfusion of the liver, isopycnic sedimentation in Percoll, and selective adherence of the cells. The Kupffer cells (KC) attach and spread on glass or plastic in serum-free medium 15 min following seeding. Cultures of KC are 90%-95% pure with about 5% liver endothelial cells (LEC), less than 1% parenchymal cells (PC) and a maximum of 5% stellate cells (SC). The LEC adhere and spread on fibronectin 60-120 min following seeding, forming cultures that are contaminated with 5-10% SC and less than 1% KC and PC. The yield of plated LEC is 50-60 X 10(6) per 200-g rat. Ultrastructural analysis shows that Percoll does not associate with the cells during the separation procedure.

The plasma clearance, tissue distribution and metabolism of hyaluronic acid were studied with a high average molecular weight [3H]acetyl-labelled hyaluronic acid synthesized in synovial cell cultures. After intravenous injection in the rabbit the label disappeared from the plasma with a half-life of 2.5--4.5 min, which corresponds to a normal hyaluronic acid clearance of approx. 10 mg/day per kg body weight. Injection of unlabelled hyaluronic acid 15 min after the tracer failed to reverse its absorption. Clearance of labelled polymer was retarded by prior injection of excess unlabelled hyaluronic acid. The maximum clearance capacity was estimated in these circumstances to be about 30 mg/day per kg body wt. The injected material was concentrated in the liver and spleen. As much as 88% of the label was absorbed by the liver, where it was found almost entirely in non-parenchymal cells. Degradation was rapid and complete, since volatile material, presumably 3H2O, appeared in the plasma within 20 min. Undegraded [3H]hyaluronic acid, small labelled residues and 3H2O were detected in the liver, but there was little evidence of intermediate oligosaccharides. No metabolite except 3H2O was recognized in plasma or urine. Two-thirds of the radioactivity was retained in the body water 24 h later, and small amounts were found in liver lipids. Radioactivity did not decline in the spleen as rapidly as in the liver. The upper molecular weight limit for renal excretion was about 25 000. Renal excretion played a negligible part in clearance. It is concluded that hyaluronic acid is removed from the plasma and degraded quickly by an efficient extrarenal system with a high reserve capacity, sited mainly in the liver.

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