Characteristics and a model for fast axoplasmic transport in nerve

Fast axoplasmic transport at a characteristic rate close to 400 mm/day is seen in a variety of different mammalian species. Particulates, proteins, polypeptide, and free amino acids are all carried down the fibers at the same rate. An hypothesis to account for such a heterogeneous transport is based on the sliding filament theory of muscle. In the neuron, a “transport filament” is synthesized in the cell body and to it the various transported species are bound. The transporting filament moves down the nerve by means of cross‐bridges. In analogy to muscle where ATP is required to supply the energy required for the cross‐bridges, fast axoplasmic transport in the nerve fiber also has been found to depend on oxidative metabolism supplying ATP.