K+ accumulation in the space between giant axon and Schwann cell in the squid Alloteuthis: effects of changes in osmolarity

Astion, M. L., Coles, J. A., Orkand, R. K. and Abbott, N. J. (1988) K+ accumulation in the space between giant axon and Schwann cell in the squid Alloteuthis: effects of changes in osmolarity. Biophysical Journal, 53(2), pp. 281-285. (doi: 10.1016/S0006-3495(88)83090-X)

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Publisher's URL: http://dx.doi.org/10.1016/S0006-3495(88)83090-X

Abstract

In a train of impulses in squid giant axon, accumulation of extracellular potassium causes successive afterhyperpolarizations to be progressively less negative. In Loligo, Frankenhaeuser and Hodgkin had satisfactorily accounted for the characteristics of this effect with a model in which the axon is surrounded by a space, width theta, and a barrier of permeability P. In axons isolated from Alloteuthis, we found that the model fitted the observations quite well. Superfusing the axon with hypotonic artificial seawater (ASW) caused theta and P to decrease, and, conversely, hypertonic ASW caused them to increase: this would be the case if both the space and the pathway through the barrier were extracellular. In some cases, in normal ASW, the afterhyperpolarizations in a train decreased very little, less than 0.7 mV. In these extreme cases, theta was estimated to be 190 nm and P to be 7 x 10(-4) cm s-1, both several times the values of 30 nm and 6 x 10(-5) cm s-1 estimated by Frankenhaeuser and Hodgkin. We suggest that in vivo the periaxonal space may be considerably wider than that seen in conventionally fixed squid tissue.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Coles, Dr Jonathan
Authors: Astion, M. L., Coles, J. A., Orkand, R. K., and Abbott, N. J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Biophysical Journal
Journal Abbr.:Biophys J.
Publisher:Cell Press
ISSN:0006-3495
ISSN (Online):1542-0086

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