遺伝性高脂血症ウサギ(WHHL-rabbit)における動脈硬化性病変に及ぼす高酸素ならびに低酸素吸入の影響

Abstract

The present study was carried out to investigate the effects of systemic hyperoxia and hypoxia on plasma lipids and atherogenesis in WHHL-rabbits which showed marked hypercholesterolemia and hypertriglyceridemia from birth.Of 15 male WHHL-rabbits (2-3 months old), six rabbits were exposed to 40% oxygen (hyperoxic) and five were exposed to 10% oxygen (hypoxic) for five hours daily on five days of each week for eight weeks. Four rabbits without such exposure were used as controls. The results were as follows:1) The levels of plasma cholesterol were not affected significantly by the hyperoxic and hypoxic exposure throughout the experimental period. Therefore, the average plasma cholesterol levels in the three groups indicated almost the same values.2) The levels of plasma triglycerides increased significantly by systemic hypoxia but were not affected by hyperoxia, and the average plasma triglyceride values were higher in the hypoxic rabbits than in the hyperoxic or control rabbits.3) The ratio of the area of sudanophilic lesions to the total intimal area of the aorta were lower in the hyperoxic rabbits, and higher in the hypoxic rabbits than in the controls. The differences between the hyperoxic and hypoxic groups were significant.4) There were no significant correlations between the extent of the aortic lesions and the levels of plasma cholesterol or triglycerides.From these results, it is suggested that the progress of atherosclerotic changes of the aorta is suppressed or promoted by systemic hyperoxia or hypoxia, respectively, not through the changes in the plasma lipid levels, but through the direct effects on the aortic wall.