Effects of prolonged bedrest on HDL metabolism and function. Different metrics of HDL metabolism and function were evaluated for the bedrest (n = 11) and the bedrest plus RVE (n = 11) groups. (a) Plasma HDL-cholesterol levels were evaluated by a commercially available kit. (b) The ability of HDL to promote [3H]-cholesterol efflux from macrophages was evaluated. [3H]-cholesterol-labeled J774.2 cells were incubated with apoB-depleted plasma (2.8%) for 3 h and the effluxed [3H]-cholesterol was quantified. Cholesterol efflux is expressed as radioactivity in the cell culture supernatant relative to total radioactivity (in the cell culture supernatant and cells) of two independent experiments, measured in duplicates. (a,b) Differences between pre-bedrest baseline and day 7 of bedrest, day 21 of bedrest and one day recovery, as well as differences between the two groups at each time point, were analyzed with RM one-way ANOVA using the Sidak’s multiple comparisons test (normally distributed data). Individual data are depicted on top of boxplots showing median and interquartile range, as well as minimum and maximum values (indicated by error bars). Significance level for the analyses was set to α = 0.05. No significant differences were observed between the two groups. Significant differences between the respective time points and the pre-bedrest baseline are indicated. HDL high-density lipoprotein, RVE resistive vibration exercise.