Jump to ContentJump to Main Navigation
Cephalopod NeurobiologyNeuroscience Studies in Squid, Octopus and Cuttlefish$
Users without a subscription are not able to see the full content.

N. Joan Abbott, Roddy Williamson, and Linda Maddock

Print publication date: 1995

Print ISBN-13: 9780198547907

Published to Oxford Scholarship Online: March 2012

DOI: 10.1093/acprof:oso/9780198547907.001.0001

Show Summary Details
Page of

PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 13 June 2021

Periaxonal ion regulation in the squid

Periaxonal ion regulation in the squid

(p.229) 16 Periaxonal ion regulation in the squid
Cephalopod Neurobiology

Y. Pichon

N. Joan Abbott

E. R. Brown

Isao Inoue

Patricia A. Revest

Oxford University Press

In the majority of animal groups, axons release K+ and take up Na+ during action potential production, with a tendency for an accumulation of K+ and depletion of Na+ in the narrow extracellular spaces adjacent to the axon. Homeostatic mechanisms are present to reduce the severity of these changes, and so limit their undesirable effects on neuronal function. This chapter reviews studies in squid giant axons to show that, under normal physiological conditions, the Schwann cell sheath around the axon has powerful mechanisms for regulating the [K+] in the periaxonal space, using a combination of passive diffusion (particularly via the transcellular glial tubular system and across its membranes) and carrier-mediated transport. The significance of this regulation for the normal function of the giant axon system in swimming and escape responses is discussed. Axons in vertebrates and invertebrates use a sequence of voltage-dependent ionic currents to generate propagating action potentials, generally an early inward Na+ current followed by a late outward K+ current. If the axon is surrounded by a narrow interstitial space, there is a tendency for K+ accumulation and Na+ depletion in the space during activity. If the axon is surrounded by a narrow interstitial space, there is a tendency for K+ accumulation and Na+ depletion in the space during activity. The axonal resting potential is relatively insensitive to small changes of [K+] in the physiological range, because the significant Na+ permeability of the membrane flattens the Nernst plot of membrane potential versus log [K+] in this range.

Keywords:   periaxonal ion, transcellular glial tubular, Nernst plot, neuronal function, homeostatic mechanisms, axon

Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.

Please, subscribe or login to access full text content.

If you think you should have access to this title, please contact your librarian.

To troubleshoot, please check our FAQs , and if you can't find the answer there, please contact us .