AJP - Cell Physiology, Vol 269, Issue 2 C341-C348, Copyright © 1995 by American Physiological Society

ARTICLES

Arachidonic acid inhibits potassium conductances in cultured rat oligodendrocytes

B. Soliven and N. Wang
Department of Neurology, University of Chicago, Illinois 60637, USA.

Arachidonic acid (AA) and its metabolites play a dual role as intracellular second messengers and as transcellular mediators of neural activity. We have previously shown that AA increases cytosolic Ca2+ in oligodendrocytes. In this work, we studied the effects of AA and other fatty acids on whole cell K+ currents of cultured rat oligodendrocytes using the patch-clamp technique. We found that 1) AA decreased the current amplitudes of both the inwardly rectifying K+ current (IKir) and the outward K+ currents (IKo) resulting in membrane depolarization; 2) AA also induced IKo current inactivation/blocked state; 3) AA appeared to act directly on K+ channels and not indirectly via its metabolic products, activation of protein kinase C, or by generation of oxygen free radicals. We have thus demonstrated an additional mechanism for AA-induced signaling in oligodendrocytes, i.e., via modulation of K+ conductances leading to membrane depolarization. The latter has been shown to influence protein phosphorylation and perhaps other important functional output of oligodendrocytes.

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