Calcium and the Mechanism of Axoplasmic Transport

Abstract

It is a truism that clinical problems will be solved through a deeper knowledge of the basic mechanisms of the body. With respect to the nervous system, our understanding has been advanced in recent years through the uncovering of a new basic aspect of nerve function, namely, the movement of materials from their site of synthesis in the nerve cell bodies outward in the fibers (Ochs, 1975). This process, termed axoplasmic transport, carries materials in the anterograde direction within nerve fibers of all sizes at a constant rate of close to 410 mm/day in all mammalian species so far examined (Ochs, 1972a). In our studies, a labeled precursor, ³H-leucine, is injected into the L7 dorsal root ganglia or into the spinal cord supplying the sciatic nerve and at later times, a crest of labeled incorporated proteins and polypeptides is seen to move down the nerve. Biochemical analysis shows that a wide range of labeled materials are moved down the fibers. Some of these materials and the later downflow behind the crest supply the axon and terminal processes with essential components required to maintain their function. Various aspects of transport, including retrograde transport and slow transport, have been touched on by the other speakers of this workshop.