Skinned smooth muscle: calcium-calmodulin activation independent of myosin phosphorylation

In chemically skinned chicken gizzard smooth muscle fibers investigated shortly after preparation, a contraction may be induced by calcium and calmodulin which is independent of myosin phosphorylation at intermediate Ca2+-concentrations. However, fibers stored for a prolonged period also contract in the absence of exogenous calmodulin and exhibit a close relationship between force development and myosin phosphorylation.