Colestipol-induced changes in LDL composition and metabolism. II. Studies in humans

Area of Science:

• Cardiovascular Science
• Lipid Metabolism
• Pharmacology

Background:

• Low-density lipoprotein (LDL) cholesterol is a key risk factor for cardiovascular disease.
• Bile acid sequestrants are used to lower LDL cholesterol levels.
• The specific effects of colestipol on LDL particle characteristics and metabolism require further investigation.

Purpose of the Study:

• To investigate the impact of colestipol hydrochloride on the composition and metabolism of human LDL.
• To determine if altered LDL particles exhibit different metabolic properties.

Main Methods:

• Colestipol hydrochloride treatment in human subjects.
• Analysis of LDL cholesterol and apolipoprotein B (apoB) levels.
• Electron microscopy and analytical ultracentrifugation to assess LDL particle size and density.
• Autologous LDL isolation and determination of fractional catabolic rates (FCR) before and during therapy.

Main Results:

• Colestipol treatment led to a disproportionate decrease in LDL cholesterol relative to apoB, reducing the LDL cholesterol/apoB ratio.
• LDL particles became smaller, denser, and had a lower cholesterol-to-protein ratio.
• The fractional catabolic rate (FCR) of LDL isolated during colestipol therapy (Rx-LDL) was significantly slower than that of LDL isolated before therapy (Con-LDL) in most subjects and studies.
• Colestipol therapy resulted in an average 29% reduction in LDL cholesterol.

Conclusions:

• Drug interventions like colestipol can alter LDL subpopulations, changing overall LDL composition.
• These compositional changes can independently affect the intrinsic metabolic behavior of LDL particles.
• Drug-induced changes in LDL composition should be considered in kinetic studies assessing therapeutic impacts.