Plasma Lipoprotein(a) Levels Showing Age-Related Changes in Diabetic and Hypertensive Individuals.

Abstract

SummaryWe measured plasma levels of lipoprotein (a) [Lp(a)] in 117 individuals. A highly significant relationship between Lp(a) and increasing age was found in hypertensive patients but not in normals. These patients also showed marked variation in both total cholesterol and low-density lipoprotein (LDL)-cholesterol levels. In diabetic subjects, despite the significant elevation in TG and very low-density lipoprotein-cholesterol, the increase in Lp(a) concentration was not significant, probably due to a more rapid clearance of triglyceride rich particle apo (a) of Lp(a) compared to the slower apo (a) catabolism in the LDL density range.Key Words: lipoprotein(a), diabetes, hypertension, age Lipoprotein (a) [Lp(a)], an antigen variant of human low-density lipoprotein (LDL), has pre-fl mobility on lipoprotein electrophoresis but floats in a high density range between 1.05 to 1.10 g/ml during ultracentrifugation. Its protein moiety consists of apolipoprotein B-100 (apo B-loo) and a specific apolipoprotein a [apo (a)] that form a macromolecular complex linked together by a disulfide bridge [1,2]. Since apo (a) has an affinity for apo B-containing lipoprotein (apo B-Lp), enhanced binding of the apo (a) of Lp(a) to the arterial wall could increase the accumulation of LDL in the matrix and thus promote the development of cardiovascular disease (CVD) [3].Many case studies showed that high Lp(a) is an independent risk factor for premature CVD and that its level has a direct correlation with the disease. Studies carried out on Lp(a) concentrations in plasma indicated that the Lp(a) level is not modified by changes in diet, life style, or therapy with most lipid-lowering drugs except nicotinic acid; rather, it is genetically controlled [4][5][6][7][8]. Lp(a) also competes with plasminogen for binding to endothelial cells and macrophages, preventing