Effect of 20 days' bed rest on the reverse cholesterol transport system in healthy young subjects

Ryoko Yanagibori, Kazuo Kondo, Yoji Suzuki, Kiyoshi Kawakubo, Tamami Iwamoto, Hiroshige Itakura, Atsuaki Gunji (Aichi Prefectural College of Nursing and Health, Aichi: National Institute of Health and Nutrition, Tokyo; and University of Tokyo, Japan). Effects of 20 days' bed rest on the reverse cholesterol transport system in healthy young subjects J Intern Med 1998; 243 : 307–12.

Objectives

To study the effects of 20 days of bed rest on HDL cholesterol, lipoprotein lipase, hepatic triglyceride lipase, cholesterol ester transfer protein and lecithin–cholesterol acyltransferase.

Design

A 20-day intervention study.

Setting

Makita general hospital.

Subjects

Five male and five female healthy participants, mean age 20.4 years, range 19–24 years.

Interventions

Twenty days of bed rest.

Main outcome measures

Lipid, lipoprotein, lipoprotein lipase, hepatic triglyceride lipase, cholesterol ester transfer protein and lecithin–cholesterol acyltransferase.

Results

Fasting HDL, HDL₂ and HDL₃ cholesterol levels decreased from 1.748 to 1.404 mmol L^?1 (P < 0.01), from 0.807 to 0.628 mmol L^?1 (P < 0.01) and from 0.939 to 0.784 mmol L^?1 (P < 0.05), respectively, while VLDL triglyceride levels increased from 0.365 to 0.754 mmol L^?1 (P < 0.05). Plasma post-heparin lipoprotein lipase activity decreased from 0.494 to 0.418 μmol mL^?1 h^?1 (P < 0.01), but plasma post-heparin hepatic triglyceride lipase activity and cholesterol ester transfer protein activity did not change during bed rest. Lecithin–cholesterol acyltransferase activity increased from 72.5 to 84.8 nmol mL^?1 h^?1 (P < 0.001).

Conclusions

Twenty days of bed rest induced a decline in HDL cholesterol levels and an increase in VLDL triglyceride levels. When considering lipoprotein lipase, hepatic triglyceride lipase, cholesterol ester transfer protein and lecithin–cholesterol acyltransferase as factors in the decreased HDL cholesterol, the contribution of lipoprotein lipase is suggested.