Effects of cholinergic compounds on the axon-Schwann cell relationship in the squid nerve fiber

  • Jorge Villegas
Part of the Faseb Monographs book series (FASEBM, volume 5)


The effects of acetylcholine, carbamylcholine, D-tubocurarine, eserine, and α-bungaro-toxin on the Schwann cell electrical potential of resting and stimulated squid nerve fibers were studied. Acetylcholine (10-7 M) and carbamylcholine (10-6 M) induce a prolonged hyper polarization in the Schwann cells of the unstimulated nerve fiber. In the presence of carbamylcholine (10-6 M) the behavior of the Schwann cell membrane to changes in the external potassium concentration approximates the behavior of an ideal potassium electrode. D-Tubocurarine (10-9 M) blocks the hyperpolarizing effects of nerve impulse trains and carbamylcholine (10-6 M), whereas at the same concentration eserine prolongs the Schwann cell hyperpolarizations induced by axon stimulation or by acetylcholine (10-7m). α-Bungarotoxin (10-9 M) also blocks the hyperpolarizing effects of nerve impulse trains and of carbamylcholine. D-Tubocurarine (10-5 M) protects the Schwann cells against the irreversible action of α-bungarotoxin. These results show the existence of acetylcholine receptors in the Schwann cell membrane. Preliminary measurements of the binding of 125I-α-bungarotoxin to the plasma membranes isolated from squid nerves also indicate the presence of acetylcholine receptors. These findings support the involvement of cholinergic mechanisms in the axon-Schwann cell relationship previously described.—Villegas, J. Effects of cholinergic compounds on the axon-Schwann cell relationship in the squid nerve fiber. Federation Proc. 34: 1370–1373, 1975.


Nerve Fiber Schwann Cell Acetylcholine Receptor External Application Hyperpolarizing Effect 
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Copyright information

© Federation of American Societies 1975

Authors and Affiliations

  • Jorge Villegas
    • 1
  1. 1.Centro de Biofísica y BioquímicaInstituto Venezolano de Investigaciones CientíficasCaracas 101Venezuela

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