Plasma protein entry and retention in the vascular wall: possible factors in atherogenesis.

Various experiments are described that relate to measuring the uptake of plasma proteins by the walls of various large blood vessels of the rabbit. The rate of uptake across the intimal surface is not uniform, there being punctate regions of elevated transport. In addition, the rate of transport appears to be considerably higher across veins, pulmonary vessels, and the ascending aorta than across more peripheral arteries. Although larger proteins such as fibrinogen and low-density lipoprotein are transported more slowly than smaller ones, they appear to be retained to a greater extent in the inner layers of arteries than in pulmonary vessels and veins. Retention is greatly enhanced when collars are placed around the arteries and may be involved in the intimal hyperplasia that is seen in such vessels. Thus it appears that it may be the relative extent of entrapment of large atherogenic proteins that determines the appearance of lesions at different sites in the cardiovascular system, in addition to the rates at which they exchange across the blood-wall interface.