Effect of chronic electrostimulation of rabbit skeletal muscle on calmodulin level and protein kinase activity

(a) Chronic electrostimulation of fast-twitch skeletal muscles makes them r esemble slow-twitch muscles. The involvement of second-messenger cascades i n this muscle reprogramming is not well understood. The goal of this study was to examine protein kinase activities and calmodulin levels as a functio n of the duration of electrostimulation, (b) Fast-twitch rabbit muscle was subjected to continuous low-frequency ele ctrostimulation for 2 weeks, The extensor digitorum longus was taken and ex amined for calmodulin concentration and cAMP-dependent (PKA), Ca2+-phosphol ipid-dependent (PKC) and Ca2+-calmodulin-dependent (CaM kinase or PKB) prot ein kinase activities. (c) Electrostimulation for 14 days led to a significant increase in total c almodulin level and PKB activity, both rising in the cytosolic fraction. Pr otein kinase C translocated to the membrane fraction, although total activi ty did not change. (d) These changes could be related with electrostimulation-induced changes in excitation-contraction coupling. (C) 1999 Elsevier Science Ltd. All righ ts reserved.