Figure 2. Effect of in situ contraction duration on skeletal muscle lysate Ca²⁺–calmodulin-dependent protein kinase II activity.

Skeletal muscle extracts 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). STIM, electrically stimulated to contract: CON, contralateral control. Data are mean ± s.e.m., n = 7–8; *Different from time 0, P < 0.05.