Metabolism of the Arterial Wall

Abstract

The enzymes of lipid, carbohydrate, protein and nucleic acid metabolism in normal and arteriosclerotic aorta have been studied (Kirk, 1963). In a survey of enzyme activities, Kirk (1969) pointed out that aortic enzymic activity could not be directly correlated with the severity or type of arteriosclerotic involvement, some activities rising and some falling (Table 1). Since it is not possible to deal with all enzymic activities in the aorta, we shall deal with those relating to that particular component which showed the greatest degree of change, namely, lipid. Smith (1965) has shown that the mucopolysaccharide content of the fatty streak was 115% of that in the normal aorta but in the fibrous and calcified plaque, the mucopolysaccharide content was 96% and 46% of normal. Collagen content was 106%, 166% and 285% that of normal in the fatty streak, fibrous plaque and calcified plaque, respectively. Lipid content rose most strikingly with progression of the lesion in the fatty streak being 312% or normal, 483% in the fibrous plaque and 1112% in the calcified plaque. Among the lipid classes, the most marked increase was that observed in the aortic cholesterol ester. This increase was observed by Windaus (1910) and was further quantitated by Böttcher (1961) and Smith (1965). The phospholipid content of the artery did not vary sharply with age and atherosclerosis, but the sphingomyelin content of human arteries showed a sharp rise in atherosclerotic lesions (Böttcher, 1961).

This work was supported in part by Research Grants HL-03299, HL-13722 and a Research Career Award (HL-00734) from the National Heart and Lung Institute and by a grant from the John A. Hartford Foundation, Inc.