Elevation of aortic proline hydroxylase: a biochemical defect in experimental arteriosclerosis

The relation of collagen synthesis to experimentally induced arteriosclerosis was studied by measuring proline hydroxylase activity. Gross aortic plaques were produced in rabbits by daily injection of epinephrine (intravenous) and thyroxine (intraperitoneal) for 4, 9, or 14 days. Activity of proline hydroxylase was significantly increased after 4 days of treatment and reached a peak, five- to sixfold increase, after 14 days of treatment. The increase in enzyme activity was correlated with the severity of observed arteriosclerosis. Increase in proline hydroxylase activity may be a possible biochemical defect in the aortas of rabbits with arteriosclerosis induced by injury.