Characterisation of Kir2.0 proteins in the rat cerebellum and hippocampus by polyclonal antibodies

Rabbit polyclonal antibodies were raised to rat Kir2.0 (Kir2.1, Kir2.2 and Kir2.3) inwardly rectifying potassium ion channel proteins. The antibody specificities were confirmed by immunoprecipitation of [35S]-methionine-labelled in vitro translated channel proteins and western blotting. Immunohistochemistry revealed a different patterns of expression of Kir2.0 subfamily proteins in the rat hind-brain (cerebellum and medulla) and fore-brain (hippocampus). Notably, only Kir2.2 protein was detected in the cerebellum and medulla, Kir2.1, Kir2.2 and Kir2.3 proteins were expressed in the hippocampus and immunostaining was not limited to neuronal cell types. Anti-Kir2.1 (fore-brain only) and anti-Kir2.2 (fore- and hind-brain) antibodies showed positive staining in macroglia, endothelia, ependyma and vascular smooth muscle cells. In contrast, anti-Kir2.3 (fore-brain only) immunostaining was limited to neurons, macroglia and vascular smooth muscle. These results indicate that specific regions within the rat fore- and hind-brain have differential distributions of inwardly rectifying potassium ion channel proteins.