IDENTIFICATION OF G-PROTEIN-REGULATED INWARDLY RECTIFYING K+ CHANNELS IN RAT-BRAIN OLIGODENDROCYTES

Rat brain oligodendroglia in culture express a dominant inwardly rectifying K+ current I-KIR which can be inhibited through G. proteins by the activation of glial G protein-coupled receptors. Electrophysiologically we have isolated in these cells several conductances of K+ inward rectifiers (Km) between 12 and 175 pS. Experiments on the single channel level with preloading or bath-application of GTPyS revealed the selective suppression of an 18 pS and maybe other K-IR conductances, possibly via a direct membrane-delimited mechanism. mRNA amplification from single oligodendrocytes together with polymerase chain reaction resulted in the isolation of IRK-type K+ channels which may correspond to the channel species negatively controlled by G proteins.