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 sp ecificities were confirmed by immunoprecipitation of [S-35]-methionine-labe lled in vitro translated channel proteins and western blotting. Immunohisto chemistry revealed a different patterns of expression of Kir2.0 subfamily p roteins in the rat hind-brain (cerebellum and medulla) and fore-brain (hipp ocampus). Notably, only Kir2.2 protein was detected in the cerebellum and m edulla, Kir2.1, Kir2.2 and Kir2.3 proteins were expressed in the hippocampu s and immunostaining was not limited to neuronal cell types. Anti-Kir2.1 (f ore-brain only) and anti-Kir2.2 (fore- and hind-brain) antibodies showed po sitive staining in macroglia, endothelia, ependyma and vascular smooth musc le cells. In contrast, anti-Kir2.3 (fore-brain only) immunostaining was lim ited to neurons, macroglia and vascular smooth muscle. These results indica te that specific regions within the rat fore- and hind-brain have different ial distributions of inwardly rectifying potassium ion channel proteins.