Fast transport system of materials in mammalian nerve fibers.

A fast transport system of materials is shown in cat sensory fibers of sciatic nerve. After injection of tritiated leucine into the lumbar seventh ganglia, the distribution of activity was measured in the sciatic nerves from 2 to 8 hours afterward. The distribution showed a crest of activity advancing down the fibers at a rate of approximately 410 millimeters per day. An intraaxonic locus of the activity was indicated by a block of the downflow induced by local freezing which causes the fibers to close off. Some of the activity in the nerve was due to free tritiated leucine, with most of it incorporated into polypeptide, soluble protein, and subcellular particulates.