Fig. 5.

Isoproterenol activates phosphorylase and inactivates glycogen synthase in soleus and extensor digitorum longus muscles. Phosphorylase (Phos) and glycogen synthase (GS) fractional activities were determined in soleus (SOL, a and c) and extensor digitorum longus muscles (EDL, b and d). Treatments consisted of basal control (BC), basal isoproterenol (BI), stimulated control (SC), and stimulated isoproterenol (SI) in the absence (−) or presence (+) of 3 mM sodium cyanide. SOL muscles were stimulated for 5 s at 100 Hz and EDL muscles for 1 s at 120 Hz. Data are expressed as mean ± SE for 5–7 muscles (numbers vary as sufficient extract was not always available). *p < 0.05; **p < 0.01; ***p < 0.001 vs. corresponding baseline values by paired t test