Fig. 3. Time-dependent changes in catalase (CAT) activity in the skeletal muscle of untreated, L-arginine-treated and L-NAME-treated rats during acclimation to cold (4±1°C). ^*P<0.05, ^**P<0.01, ^***P<0.001 compared with the control acclimated to room temperature (22±1°C). ^#P<0.05, ^##P<0.0, ###P<0.001 compared with the untreated group at the same time of cold acclimation.