Inward and outward rectifying potassium currents set membrane potentials in activated rat microglia.
Activation of cultured rat microglial cells with lipopolysaccharide (LPS), induced outward rectifying K+ (K(V)) current in addition to already existing inward rectifying K+ current (K(IR)). By measuring zero-current membrane-potentials using whole-cell patch-clamp method, we showed that K(V) current plays a direct role in setting membrane potential to near -45 mV. Since the membrane potentials of microglia show two prominent peaks at -45 and -70 mV, we hypothesize that K(IR) current might set the membrane potential to near -70 mV. We observed that cells with larger K(IR) current had a zero-current membrane-potential at around -70 mV, and that blocking of K(IR) current with Ba2+ depolarized membrane potentials to near -45 mV. These results indicate that the amounts of K(IR), and K(V) current determine the zero-current membrane-potentials in LPS-activated microglia.
Chung
S
S
Department of Physiology, Chung-Ang University College of Medicine, Seoul, South Korea. chung10@nownuri.net
Jung
W
W
Lee
M Y
MY
D000818:Animals; D001464:Barium / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying; D051381:Rats; D017207:Rats, Sprague-Dawley
D008070:Lipopolysaccharides; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D001464:Barium