Kinetics of low density lipoprotein interactions with rabbit aortic wall following balloon catheter deendothelialization.

Abstract

The kinetics of the interaction of circulating lipoproteins with the balloon catheter-injured aortic wall of rabbits were investigated. The fate of radioiodinated low density lipoprotein (LDL) was followed up to 48 hours after intravenous injection and compared with radioiodinated albumin injected simultaneously. The accumulation of LDL was calculated from the radioactivity in the aortic tissue divided by the average specific activity, measured from the area below the plasma radioactivity versus the time curve, and expressed as cpm/ml/hr. It was observed that the aortic area of endothelial regeneration (AER), which is relatively impermeable to Evans blue dye and shows very little albumin concentration, accumulated considerably more LDL than control (uninjured) tissues. Furthermore, removal of labeled lipoprotein from the intima during a 24-hour efflux period following the initial 48-hour loading period indicated that there was greater removal from normal and deendothelialized aortic (DEA) tissues than from neointima covered by endothelium. These findings are consistent with previous observations indicating changes in the morphological and chemical composition of AER. There is evidence that greater neointimal lipid accumulation in response to endothelial injury parallels the concentration of glycosaminoglycans (GAG). The relatively increased accumulation of label in AER, while plasma-specific activity is rapidly decreasing, indicates that there may be an ionic interaction of GAG with LDL in the AER.