Voltage-gated potassium currents in cultured ovine oligodendrocytes.
Cultured oligodendrocytes (OLGs) develop processes and form myelin following attachment to a substratum. We applied the whole-cell voltage-clamp technique to identify and characterize the ionic currents of OLGs in culture. Within 2 d after attachment, OLGs extended processes and began to express an outward current that represents a composite response of an inactivating/transient component and a non-inactivating component. The current had a reversal potential of -66 mV and was sensitive to potassium channel blockers. After 4-5 d in culture, the transient component was less prominent, often accompanied by an increase in noninactivating or steady-state outward current. In addition, there was an increase in inward rectifier current. Four of 7 cells that failed to develop processes exhibited only linear high-resistance membranes. We conclude that cultured OLGs express 3 voltage-gated potassium conductances: (1) a transient outward current, (2) a noninactivating outward current, and (3) an inward rectifier current. The sequential appearance of the several currents may relate, at least in part, to process formation.
Soliven
B
B
Department of Neurology, University of Chicago, Illinois 60637.
Szuchet
S
S
Arnason
B G
BG
Nelson
D J
DJ
D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D002586:Cesium / Q000494:pharmacology; D004586:Electrophoresis; D007700:Kinetics; D008564:Membrane Potentials; D009457:Neuroglia / Q000502:physiology*; D009836:Oligodendroglia / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D012756:Sheep; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D000631:Aminopyridines; D013757:Tetraethylammonium Compounds; D002586:Cesium; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D011188:Potassium