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

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