K-ir 4.1 channel expression in neuroblastoma X glioma hybrid NG108-15 cellline

study a possible involvement of inwardly rectifying K+ 4.1 (K-ir 4.1) chann els in neural cell development, RT-PCR, immunocytochemistry and whole-cell patch-clamp techniques were used to assess expression of K-ir 4.1 channels in proliferating and differentiated NG108-15 cells. RT-PCR revealed co-expr ession of K-ir 4.1 and rat ether-a-go-go-related gene (R-ERG) mRNAs in both proliferating and differentiated cells. The relative K-ir 4.1 mRNA concent ration increased markedly as cells progressed from undifferentiated to diff erentiated cells, K-ir 4.1-immunoreactivity was barely detectable in undiff erentiated cells, but clearly detected in differentiated cells, indicating that K-ir 4.1 gene and protein expressions are developmentally regulated. H owever, corresponding K-ir 4.1 current could not be detected in differentia ted cells using whole-cell patch-clamp recording. The 'silent' channel/rece ptor, often found in tumor cells, may carry genetic defects, which prevent functional expression of the channel. NG108-15 may serve as unique model fo r studying the relationship between the expression of an ion channel gene a nd the electrophysiological phenotype it encodes. (C) 1999 Published by Els evier Science B.V. All rights reserved.