RESUMO
In this study we have demonstrated that in native bile, lipids are organized in the form of a lipoprotein (bile LP) carrying albumin as apoprotein. The lipid composition of bile LP is almost identical to lipoprotein-X (LP-X, the characteristic lipoprotein of cholestasis). However, it differs from LP-X inits protein/lipid ratio and immunological and electrophoretic characteristics. Bile lipoprotein can be converted into "LP-X-like" material in vitro by adding albumin or serum to native bile. The LP-X-like material formed in vitro has physicochemical and chemical characteristics similar or identical to LP-X isolated from serum. As bile lipoprotein can be converted into LP-X-like material by the addition of albumin to bile, LP-X can be converted into bile-LP-like particles by adding bile salts to a LP-X-positive serum. Furthermore, experimental connection of the common bile duct to the vena cava is followed after a few hours by the appearance of LP-X-like material in the plasma. These facts taken together strongly suggest that bile LP is a precursor lipoprotein for LP-X and that it refluxes into the plasma pool under cholestatic conditions.
Assuntos
Ácidos e Sais Biliares/metabolismo , Bile/metabolismo , Lipoproteínas/metabolismo , Animais , Ductos Biliares/fisiologia , Sítios de Ligação , Cateterismo , Colesterol/sangue , Cães , Humanos , Imunodifusão , Imunoeletroforese , Lipoproteínas/sangue , Masculino , Microscopia Eletrônica , Fosfolipídeos/sangue , Testes de Precipitina , Ligação Proteica , Triglicerídeos/sangueRESUMO
We describe a fast and easy method for routine quantitation of the abnormal lipoprotein, lipoprotein-X. The procedure is based on densitometry of precipitation areas obtained for it after serum electrophoresis in agar gel followed by precipitation with polyanions. The coefficient of variation was less than 3% in one series. Results were linearly related to concentration in the range 0.063 to 6.3 g/liter.
Assuntos
Colestase/sangue , Lipoproteínas/sangue , Precipitação Química , Densitometria , Eletroforese em Gel de Ágar , Humanos , Imunoeletroforese , MétodosRESUMO
Based on a previously described technique [Clin. Chem. 19, 737 (1973)] of precipitating plasma lipoproteins with polyanions after their electrophoretic separation in gels, a new method is presented for measuring normal plasma lipoproteins densitometrically. The method is fast and easy; the CV for beta-, pre-beta-, and alpha-lipoproteins was less than 5% in one series. Results are linearly related to concentration up to 10 g of total lipoprotein per liter. No unusual equipment is required. Standardization is done with the aid of a commercially available filter. Total plasma cholesterol and cholesterol calculated from quantified lipoprotein fractions were highly (r = 0.963) correlated.