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 micromol 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.