In GH3/B6 cells at least two different inward K+ currents are observed that are regulated by thyrotropin-releasing hormone and somatostatin, respectively. Using a polymerase chain reaction based approach a cDNA was isolated and functionally expressed in human embryonic kidney cells that encodes an inward rectifier K+ channel, rIRK3, with a predicted molecular mass of 49.7 kDa. Corresponding transcripts of 2.6 kb have been detected in rat brain, pituitary and GH3/B6 cells. In situ hybridization revealed that rIRK3 mRNA is distributed throughout the brain and occurs predominantly in the piriform cortex, indusium griseum, supraoptic nucleus, facial nucleus and cerebellar Purkinje cells.
