Dissociation of [ 3H]cholesterol and 125I-labelled plasma protein influx in normal and atheromatous rabbit aorta : A quantitative histochemical study

Abstract

Summary The concentrations of [ 3 H]cholesterol, [ 125 I]albumin, [ 125 I]globulin and [ 32 P]-lipid were determined in multiple consecutive layers of normal and atheromatous rabbit aortic wall at 1, 2 and 4 days after injection of isotope. The isotope-counting results were confirmed by dark-ground autoradiography. The results show that the concentration gradient of [ 3 H]cholesterol slopes mainly from inside-outwards in normal and all atheromatous arteries. Conversely, the gradients for [ 125 I]albumin, and [ 125 I]gb, γ-globulin slope from outside-inwards in normal and slightly atheromatous aortas (plaques 120 μ depth). However, in 3 out of 4 segments of severely atheromatous vessels (plaques > 170 μ depth), the gradients for 125 I-labelled plasma proteins sloped from inside-outwards. These observations raise the possibility that plasma lipoproteins are not the vehicles concerned with transport of cholesterol across normal and slightly atheromatous arteries. It is tentatively suggested that endogenously synthesized phospholipid or protein may be the vehicles involved in cholesterol transport across the intact or relatively intact arterial wall. The limited results reported here on severely atheromatous aortas suggest that plasma proteins may leak directly from the lumen into gross lesions.