Table 3.

Bed rest effect on vastus lateralis muscle glutathione kinetics parameters

Glutathione	Baseline	Bed rest	P
FSR (% day−1) (n= 9)	268 ± 61	408 ± 47	0.07
Concentration (mmol (kg wet tissue)−1) (n= 10)	2.3 ± 0.2	2.7 ± 0.1	0.30
ASR (mmol (kg wet tissue)−1 day−1) (n= 9)	5.5 ± 1.1	11.0 ± 1.5	0.02

Glutathione fractional synthesis rate (FSR), concentration and absolute synthesis rate (ASR) measured in vastus lateralis by metabolic tests (Fig. 1) in ambulatory conditions (Baseline) and after 33 days of bed rest (Bed rest). Values were derived from isotopic enrichments measured by gas chromatography–mass spectrometry analyses performed in muscle biopsies taken at the end of metabolic tests. Concentration values were assessed by internal standard approach, while FSR and ASR were calculated by the novel one-sample, double-tracer approach. Data are presented as means ±s.e.m. Statistical analysis was performed by Student's t test.