Vascular enzyme activity changes accompanying the induction of experimental atherosclerosis: Part 2. Rats fed excess vitamin D

Abstract

Male albino rats were fed a large excess of vitamin D in oil (Calciferol Spofa), and changes in aortic enzyme activities were studied. It is known that a characteristic feature of the aortae of such rats is a very early and intense reaction of their connective tissue, leading to the formation of a sort of vascular scar tissue. It was found that the aortae of calciferol-fed rats reveal, in addition to adecrease in esterolytic activity, early increases in the activities of phosphomonoesterase I and II, and of 5'-nucleotidase. The activities of the tricarboxylic acid cycle enzymes do not change in these early stages of the experiment. These results oppose those found in rats fed “Harthroft's diet”, where the aortae display endothelial lipid accumulation without a connective tissue reaction. Such findings are consistent with the view that changes in vascular phosphomonoesterase activities (including 5'-nucleotidase) might reflect primary or secondary connective tissue alterations, while the decreased activity of respiratory enzymes might in some way be related to other events, in particular to the accumulation of lipids in the vessel wall.