Increased collagen prolyl hydroxylase activity in the aortic wall of rabbits exposed to chronic hypoxia.

The activity of collagen prolyl hydroxylase in aortic wall was studied in rabbits exposed to chronic 10% ambient oxygen tension for 30 days. Prolyl hydroxylase in rabbit aorta was shown to be similar to the enzyme from other sources in that it required molecular oxygen, alpha-ketoglutarate, ferrous iron and ascorbate for its activity. The activity of prolyl hydroxylase was increased to 180% of controls in the intima-media samples from rabbits exposed to hypoxia. No atherosclerotic lesions could be seen in arteries of animals kept in chronic hypoxia. If the arteries of rabbits were injured with a single mechanical dilatation, the activity of prolyl hydroxylase increased more than 2-fold, as reported previously. The exposure of these animals to chronic hypoxia further elevated the prolyl hydroxylase activity.