An in vitro method for the study of cholesterol uptake at the endothelial cell surface of the rabbit aorta

The intima-media of 2 hemisegments taken from the same aorta at the same level were shown to take up fairly equal amounts of labelled cholesterol when incubated in the same serum, which means control conditions can be easily established.

Abstract

Abstract In order to study the mechanism for the uptake of cholesterol at the intimal surface of the thoracic aorta of normal rabbits an in vitro method was developed. 1. 1.The metabolic activity of the aortic segments similar to those used in the cholesterol uptake experiments was estimated from the determination of 2 parameters, viz. the oxygen consumption rate and the rate of lactic acid production. At least 85% of catabolized glucose was converted to lactic acid. 2. 2.The serum used in the experiments on the uptake of [14C]cholesterol by aortic segments was labelled with [4-14C]cholesterol by an in vivo method. Polyvinyl chloride block electrophoresis showed the labelled cholesterol to be distributed almost exclusively in the α- and β-globulin regions. The specific activities of free and esterified cholesterol in the serum were approximately equal. 3. 3.Following incubation of aortic segments in serum containing labelled cholesterol, the preparation of an intima-media layer from the central part of the incubated segments made it possible to measure the endothelial uptake of labelled cholesterol. 4. 4.Among the animals, some variation was found in the 4-h uptake of labelled cholesterol by intima-media, but the intima-media of 2 hemisegments taken from the same aorta at the same level were shown to take up fairly equal amounts of labelled cholesterol when incubated in the same serum. Hence control conditions can be easily established.