Determinants of the atherogenic flux of low-density lipoprotein into arteries.

Evidence is provided that in anaesthetized rabbits the atherogenic uptake of low-density lipoprotein (LDL) by arterial walls is accelerated by norepinephrine at its physiological concentrations in rabbit and human blood. The principle of the experiments was to compare the uptake of intravenously injected, radioactively labelled LDL, methylated to prevent removal by high-affinity receptors, in the two carotid arteries of anaesthetized rabbits after infusing low concentrations of norepinephrine noradrenaline into one carotid and saline as control into the other, the volume rates of infusion being about 1% of the carotid blood flows. The results thus obtained may contribute towards an explanation for the accelerated atherosclerosis and the increased incidence of its clinical manifestation in conditions associated with elevated blood norepinephrine concentrations, including the episodic increases associated with stress and cigarette smoking as well as the more persistent increases caused by phaeochromocytoma.