Some characteristics of myotubes cultured from slow and fast chick muscles

Explant cultures were prepared from the slow anterior latissimus dorsi muscle and the fast posterior latissimus dorsi muscle of 15 day chick embryos. The morphology and growth pattern of myotubes from the two types of muscle were very similar. Intracellular microelectrode studies did not reveal consistent differences between the myotube types in regard to resting potential, input resistance, input time constant, or ability to produce active electrogenic responses. It is suggested that specific differentiation of the two muscles is determined by their innervation.