K_vα1 channels in murine arterioles: differential cellular expression and regulation of diameter

The primary objectives of this study were to reveal cell-specific expression patterns and functions of voltage-gated K⁺ channel (K_vαl) subunits in precapillary arterioles of the murine cerebral circulation. K_vαl were detected using peptide-specific antibodies in immunofluorescence and Western blotting assays. K_vl.2 was localized almost exclusively to endothelial cells, whereas K_vl.5 was discretely localized to the nerves and nerve terminals that innervate the arterioles. K_vl.5 also localized specifically to arteriolar nerves in human pial membrane. K_vl.5 was notable for its absence from smooth muscle cells. K_v1.3, K_vl.4, and K_vl.6 were localized to endothelial and smooth muscle cells, although K_v1.4 had a low expression level. K_vl.1 was not expressed. Therefore, we show that different cell types of pial arterioles have distinct physiological expression profiles of K_vαl, conferring the possibility of differential modulation by extracellular and second messengers. Furthermore, we show recombinant agitoxin-2 and margatoxin are potent vasoconstrictors, suggesting that K_vαl subunits have a major function in determining arteriolar resistance to blood flow.