External detection of axoplasmic flow using radionuclides

A radiolabelled pulse for the simultaneous study of anterograde and retrograde axonal transport

A technique is described for producing a pulse of [35S]methionine-labelled material which is axonally transported in amphibian sciatic nerve maintained in vitro. Using a position-sensitive detector of ionizing radiation, it is possible to continuously observe the movement of the pulse in the anterograde direction and, following turnaround at a ligature, the movement of a fraction of the pulse in the retrograde direction. Two sources of contaminant activity, which would otherwise interfere with observation of the pulse, are discussed and shown to be avoidable.

The design and construction of a multiple proportional counter used to study axonal transport

The design and construction of a multiple proportional counter, a position-sensitive detector of ionizing radiation, are described. Both the mechanical and electronic aspects are discussed. Testing procedures are outlined, and test values are cited.