The kinematics of turnaround and retrograde axonal transport

Publisher Website
Google Scholar
Abstract
Rapid axonal transport of a pulse of 35S-methionine-labelled material was studied in vitro in the sensory neurons of amphibian sciatic nerve using a position-sensitive detector. For 10 nerves studied at 23.0 ± 0.2°C it was found that a pulse moved in the anterograde direction characterized by front edge, peak, and trailing edge transport rates of (mm/d) 180.8 ± 2.2 (±SEM), 176.6 ± 2.3, and 153.7 ± 3.0, respectively. Following its arrival at a distal ligature, a smaller pulse was observed to move in the retrograde direction characterized by front edge and peak transport rates of 158.0 ± 7.3 and 110.3 ± 3.5, respectively, indicating that retrograde transport proceeds at a rate of 0.88 ± 0.04 that of anterograde. The retrograde pulse was observed to disperse at a rate greater than the anterograde. Reversal of radiolabel at the distal ligature began 1.49 ± 0.15 h following arrival of the first radiolabel. Considerable variation was seen between preparations in the way radiolabel accumulated in the end (ligature) regions of the nerve. Although a retrograde pulse was seen in all preparations, in 7 of 10 preparations there was no evidence of this pulse accumulating within less than 2–3 mm of a proximal ligature; however, accumulation was observed within less than 5 mm in all preparations.