Inhibition by E-64-c of neurofilament degeneration induced by calcium ions

Short segments of rat sciatic nerve were incubated in calcium-free and calciumcontaining media. with or without E-64-c, which is a potent inhibitor of calciumactivated neutral protease (CANP). Triton X-100 was added to 1% to all media to accelerate the penetration of calcium into nerve tissues. After incubation, nerve segments were homogenized and the extracted proteins were analyzed by sodium dodecyl sulfate (SDS) polyacrylamide slab gel electrophoresis. Selective loss of 200,000, 160,000, and 68,000 molecular weight (MW) proteins, which are components of neurofilaments, was observed in medium containing calcium. However, in medium containing calcium with E-64-c and calcium-free medium, these chemical changes did not occur. This finding strongly suggests the presence of an enzyme in peripheral nerves which is similar, if not identical, to CANP and has an effect on degradation of neurofilaments.