Dependence of Fast Axoplasmic Transport in Nerve on Oxidative Metabolism

Abstract —A crest of labelled activity moving down the sciatic nerve at 401 ± 35 mm/day after injection of the L7 dorsal root ganglion of the cat with L‐[ 3 H]leucine characterizes fast axoplasmic transport of materials and has been studied with regard to its dependence on oxidative metabolism. Transport of labelled materials in vitro occurred if the nerve was supplied with O 2 or 95 % O 2 + 5 % CO 2 . Transport was not dependent upon continuity of the fibres with the ganglionic soma. Asphyxiation (N 2 ) rapidly blocked fast transport in vitro. Likewise NaCN or dinitrophenol in an O 2 atmosphere both effectively block fast transport within 15 min. Tetrodotoxin and procaine, agents which block excitation of the membrane, had no effect on fast transport. The inference is that oxidative metabolism supplies the energy required by the molecular mechanism underlying fast axoplasmic transport.