Anterograde to retrograde reversal of fast axonal transport within cold blocked and rewarmed intact axons.
The possibility that anterograde to retrograde reversal of axonal transport might take place in mid axon at a site distant from any nerve termination was investigated in sciatic nerve preparations from Xenopus laevis. The nerve, containing a pulse of anterogradely transported protein labeled with [35S]methionine, was kept in a two-compartment temperature controlled chamber. One compartment containing the proximal nerve was maintained at room temperature throughout the duration of an experiment while the second compartment containing the distal nerve, and separated from the first by a thermal barrier, was initially cooled to 3-4 degrees C and later warmed to room temperature. Transport of labeled proteins in the nerve was detected with a position-sensitive detector of ionizing radiation. With the distal portion of the nerve cold, the pulse of labeled protein transported up to the thermal barrier and stopped. When the distal part of the nerve was warmed to room temperature, retrograde and anterograde pulses of label propagated away from the thermal barrier with no time delay. The retrograde pulse could be collected on the distal side of a proximally placed tie and could be eliminated by treatment of the proximal nerve with vinblastine or dinitrophenol. Functional and structural evidence indicated that the cold block and thermal barrier were not destructive to the axons. Electron microscopy showed that the numerical density of axonal microtubules distal to the cold block was decreased about seven fold during the cold treatment and that this decrease could be prevented by 10 mumol/l taxol.(ABSTRACT TRUNCATED AT 250 WORDS)
Smith
R S
RS
Department of Anatomy, University of Alberta, Edmonton, Canada.
Snyder
R E
RE
D000818:Animals; D001369:Axons / Q000378:metabolism*; D001692:Biological Transport; D003080:Cold Temperature; D005260:Female; D006358:Hot Temperature; D008870:Microtubules / Q000378:metabolism; D009407:Nerve Block / Q000379:methods*; D011108:Polymers / Q000378:metabolism; D012584:Sciatic Nerve / Q000378:metabolism; D014982:Xenopus laevis
D011108:Polymers