Neurotrophic effects on the electrical properties of cultured muscle produced by conditioned medium from spinal cord explants.

The passive electrical properties of cultured chick skeletal muscle are significantly altered when the muscle is co-cultured with spinal cord explants. A reduced transverse membrane resistance appears to be responsible for the smaller values of input resistance, space constant, and time constant observed in co-cultures relative to those observed in pure muscle cultures. In this report, we show that neuromuscular junctions are not required in order to observe this neurotrophic effect because medium from spinal cord explant cultures is capable of producing the same reduction in transverse membrane resistance as the co-culturing of spinal cord explants with muscle. Control medium from liver explant cultures has no effect on muscle passive electrical properties. These results indicate that a trophic substance which is capable of regulating the electrical properties of excitable cells is released into the culture medium by spinal cord explants.