Velocity of axonal transport of labeled protein is not dependent on local concentration

The velocity of axonal transport of protein labeled with [3H]leucine was determined in rat sciatic nerve sensory axons after reversible cooling of the nerve, which provoked a local accumulation of transported material. The velocity of the wavefront of the labeled protein, as well as the slope of the wavefront, was not affected by the duration of cold-block prior to rewarming. In addition, the velocity and slope did not change as the wavefront moved distally from the site of block. In these axons, therefore, velocity of axonal transport is independent of the local concentration of rapidly transported protein.