Abstract
Fast axonal transport of radiolabeled proteins was studied in vitro in desheathed spinal nerves from frog. The replacement of the NaCl of the medium by LiCl reduced by 58% the amount of radiolabeled proteins which accumulated at a ligature, but its replacement by choline chloride did not inhibit transport. The replacement of NaCl by sodium isethionate led to a 32% reduction in the quantity of protein-bound radioactivity at the ligature. The results suggest that Cl ions are essential to maintain fast axonal transport, and that Na+ may also be important.