Effect of lipoprotein-X on lipid metabolism in rat kidney

• Published in: Molecular and cellular biochemistry 1997-08, Vol.173 (1-2), p.17-24
• Main Authors: O, K, Ly, M, Fang, D Z, Frohlich, J, Choy, P C
• Format: Article
• Language: English
• Subjects: 1-Acylglycerophosphocholine O-Acyltransferase - drug effects; 1-Acylglycerophosphocholine O-Acyltransferase - metabolism; Acetates - metabolism; Animals; Cholesterol; Choline - metabolism; Esters; Humans; Kidney - enzymology; Kidney - metabolism; Kidney - ultrastructure; Kidneys; Lecithin Cholesterol Acyltransferase Deficiency - metabolism; Lipid Metabolism; Lipids; Lipids - analysis; Lipoprotein-X - administration & dosage; Lipoprotein-X - pharmacology; Lipoproteins - pharmacology; Male; Microsomes - enzymology; Perfusion; Phospholipases A - drug effects; Phospholipases A - metabolism; Radioactivity; Rats; Rats, Sprague-Dawley; Rodents
• ISSN: 0300-8177; 1573-4919
• DOI: 10.1023/A:1006836704042

Lipoprotein-X (Lp-X) is found in the plasma of patients with familial lecithin: cholesterol acyltransferase (LCAT) deficiency syndromes. The majority of the patients with this disorder develop progressive glomerulosclerosis. In this study, the effect of Lp-X on lipid metabolism in perfused rat kidney was investigated. Lp-X was isolated from plasma of patients with familial LCAT deficiency by sequential ultracentrifugation and gel filtration column chromatography. Rat kidneys were perfused for 1-2 h with Krebs-Henseleit buffer containing 20 microM [1-(14)C]acetate or 20 microM [Me-3H]choline. In the presence of Lp-X, no significant difference in the incorporation of radioactivity into triglycerides, cholesterol, phosphocholine, CDP-choline and sphingomyelin was observed. However, incorporation of radioactivity into cholesteryl esters and phosphatidylcholine was significantly elevated in Lp-X perfused kidneys. The contents of cholesterol, cholesteryl esters and phosphatidylcholine were also significantly increased in Lp-X perfused kidneys. The increase in lipid content in the Lp-X perfused kidney is attributed to the direct deposition of Lp-X lipids into the organ. The increase in the labelling of cholesteryl esters was attributed to the increase of available substrate (cholesterol) for the acyl-CoA:cholesterol acyltransferase (ACAT) reaction. The increase in phosphatidylcholine labelling was caused by a reduced turnover of the newly synthesized labelled phosphatidylcholine during Lp-X perfusion.