Abstract
It has been elucidated that the enhanced permeability plays an important role in the initiation and progression of atherosclerosis. In this paper, localization of fibrin and β-lipoprotein in the normal and atherosclerotic human aorta and various arteries was observed by immuno-histochemical technique. The permeability pattern of the aorta, coronary artery and basilar artery of the rabbits at the ultrastructural level, including the influence of hypercholesterolemia and epinephrine administration, was also observed.
1. Fibrinogen and β-lipoprotein might pass through the aortic and larger arterial walls of the human. Endothelium and elastic membrane of the arterial wall might act as barriers to the passage of the plasma protein.
The impairment of this filtration process and/or the increased permeability of fibrinogen and β-lipoprotein in the arterial wall would result in the deposition of fibrin and/or lipid which might play an important role in the development and progression of atherosclerosis.
2. Human aorta, coronary artery and basilar artery showed different architectural and biochemical characteristics.
3. Ferritin molecules were observed in the caveolae and vesicles of the endothelial cells and in the subendothelial space of the aorta and coronary artery of the rabbits, but were not observed in the abluminal caveolae and subendothelial space of the basilar artery. Peroxidase was observed in the caveolae, vesicles and intercellular space of the endothelial cells and in the subendothelial space of the aorta and coronary artery, but was not observed in the intercellular space and subendothelial space of the basilar artery.
Unlike the aorta and coronary artery, the intima of the basilar artery showed the barrier function due to the paucity of caveolae and vesicles and the presence of the zonula occuldens in all of the intercellular junctions.
4. The aortic intima of the rabbits fed cholesterol for one week showed slightly enhanced permeability to peroxidase, but not to ferritin. Permeability to peroxidase was markedly increased and incorporation of ferritin molecules into the endothelial cells was slightly increased in the fatty streaks of the aorta of the rabbits fed cholesterol for 16 weeks.
The intima of the basilar artery showed neither foam cell accumulation nor altered permeability pattern even after 16 weeks-cholesterol feeding.
5. The aortic intima of the rabbits showed slightly enhanced permeability to peroxidase one hour after the subcutaneous administration of 0.5mg/kg epinephrine. The intima of the basilar artery showed no altered permeability pattern under the same condition.
Increased permeability to peroxidase was found in the thickened fibrous intima of the coronary artery of the rabbits administered 0.5mg/kg epinephrine subcutaneously for two months.
