Differences in the processing of chylomicron remnants and beta-VLDL by macrophages.

摘要: To gain a detailed understanding of those factors that govern the processing dietary-derived lipoprotein remnants by macrophages we examined uptake and degradation rat triacylglycerol-rich chylomicron cholesterol-rich beta-very low density (beta-VLDL) J774 cells primary cultures mouse peritoneal macrophages. The level cell associated 125I-labeled beta-VLDL reached similar equilibrium within 2 h incubation at 37 degrees C. However, was two to three times greater than each time point examined, with rates 161.0 +/- 36.0 60.1 6.6 ng degraded/h per mg protein, respectively. At extracellular concentrations protein or cholesterol, relative rate cholesteryl ester hydrolysis from [3H]cholesteryl oleate/cholesteryl [14C]oleate-labeled one-third one-half similarly labeled beta-VLDL. reduction in remnant occurred absence remnant-induced alterations (LDL) receptor recycling retroendocytosis either lipoprotein. internalization remnants, initial 0.21 ng/min for 0.39 dependent on lysosomal enzyme activity: preincubation lysosomotropic agent monensin reduced both lipoproteins 90%. pH-dependent enzymes isolated 50% difference ratio used greatest ratios 50. lysosomes 30-40% 25-50 micrograms oleic acid/ml, suggesting released free fatty acids could cause slower remnants. Thus, differences different compositions are determined least factors: 1) 2) degradation.