Rapid orthograde transport of 32P-labelled material in amphibian sensory axons: a multiwire proportional chamber study

Abstract

A multiwire proportional chamber was used to follow the axonal transport of material labelled with [32P]orthophosphate in dorsal root ganglion (DRG) – sciatic nerve preparations of Xenopus laevis and Rana catesbiana. The DRG were exposed to label for a period of 4 h following which there was a period of continued delivery of labelled material to the nerve for up to 18 h. The front of the labelled material in the nerve moved at a velocity of 160–170 mm/24 h at room temperature (22.5–23.5 °C). Sectioning the nerve at a proximal position showed that labelled material behind the front moved at a similar rapid velocity. Experiments in which the nerve was sectioned showed that some of the rapidly transported label appeared to be deposited into a relatively stationary phase. Extrapolation of the results indicated that the delay between the presentation of the label to the DRG and the onset of the transport of labelled material in the nerve was 4–6 h. The rapid transport of the label was inhibited by vinblastine sulphate at concentrations of 130–950 μM. Most of the rapidly transported material was found to be in a chloroform–methanol extractable form. In conclusion, 32P labels materials whose transport dynamics are very similar to those observed when [35S]methionine is used as the precursor.