Figure 5. Effect of exercise duration on skeletal muscle immunoprecipitate Ca²⁺–calmodulin-dependent protein kinase II activity.

Ca²⁺–calmodulin-dependent protein kinase II (CaMKII) was immunoprecipitated from skeletal muscle extracts and immunoprecipitates were assayed in vitro for CaMKII activity in the presence (i.e. maximal activity; top panel) or absence (i.e. autonomous activity; middle panel) of Ca²⁺ and calmodulin. The bottom panel shows the autonomous activity expressed relative to the maximal activity (i.e.% maximal). Data are mean ± s.e.m., n = 8. †P < 0.01 versus time 0 and 60 min; *P < 0.05 versus time 0.