Fig. 4.

Skeletal muscle protein synthesis increased from early to late winter. Protein synthesis in hindlimb muscle, heart, liver and intestine was detected by in vivo SUnSET in four summer-fasted ground squirrels (label 1), and compared with five early (label 2) and six late winter aroused hibernators after at least five consecutive days of torpor (label 3). Early winter animals were sampled 33–35 days after the onset of hibernation; late winter animals were sampled after 78–106 days. Protein synthesis is expressed relative to summer-fasted levels and does not change in the heart, liver or intestine across the time points analyzed (ANOVA, P>0.05). Skeletal muscle protein synthesis decreased in early winter, relative to both the summer baseline and the late winter hibernators (asterisk, ANOVA, P<0.05).