title: Influence of age on the metabolism of plasma low density lipoproteins in healthy males.
abstract: The plasma concentration of the atherogenic low density lipoproteins (LDL) increases with age. To clarify the mechanism of this change, we studied the kinetics of autologous 125I-LDL apolipoprotein B (apo B) in 41 normolipidemic, nonobese healthy males. For comparison, they were divided into three age groups: young, 21-39 yr (n = 18), middle-aged, 40-59 yr (n = 11), and old, 60-80 yr (n = 12). The levels of plasma LDL cholesterol and LDL apo B increased from respectively 3.4 +/- 0.1 (SEM) mmol/liter and 86 +/- 2 mg/dl in the young to 4.1 +/- 0.1 mmol/liter and 95 +/- 3 mg/dl in the old (P less than 0.01), and this increase was linked to a progressively decreased (r = -0.38, P less than 0.02) fractional catabolic rate of LDL apo B (0.348 +/- 0.010 pools per day in the young vs. 0.296 +/- 0.009 pools per day in the old, P less than 0.01). The production rate of LDL apo B did not differ significantly between the groups. The reduced fractional catabolic rate of LDL apo B in the old was not associated with a decrease in binding affinity of the LDL particle to its receptor, as judged from its ability to compete for 125I-LDL fibroblast binding. When hepatic LDL receptor expression was stimulated by cholestyramine treatment in six old males, their LDL apo B fractional catabolic rate increased to the levels observed in the young subjects. We conclude that the increase in LDL which normally occurs with age is explained by a reduced capacity for its removal, and hypothesize that this is mediated via a reduced hepatic LDL receptor expression.
authors.affiliation: Department of Medicine, Karolinska Institute, Huddinge University Hospital, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Ericsson
authors.forename: M
authors.initials: M
authors.lastname: Eriksson
authors.forename: S
authors.initials: S
authors.lastname: Vitols
authors.forename: K
authors.initials: K
authors.lastname: Einarsson
authors.forename: L
authors.initials: L
authors.lastname: Berglund
authors.forename: B
authors.initials: B
authors.lastname: Angelin
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D008077:Lipoproteins, LDL