ABSTRACT
14C-labelled acetylcholine was found to penetrate rapidly into the tissues of the intact abdominal nerve cord. Uptake in the presence of 10−4 M eserine occurred as a two-stage process, the initial rapid influx being identified as the penetration into the extracellular system of the nerve cord.
There was a more rapid accumulation of radioactivity in normal preparations as compared with those treated with 10−4 M eserine, presumably as a result of intracellular uptake of the products of hydrolysis of the acetylcholine.
The level of radioactivity in the rapidly exchanging fraction was consistent with the hypothesis that the acetylcholine ions were distributed in the extracellular fluid according to a Donnan equilibrium with the haemolymph in eserinized preparations.
These results are discussed in relation to the possible physiological role of acetylcholine in synaptic transmission in this insect.
