A: immunoblot using chicken antibody to ROMK in homogenates of dog (n = 2) bladder smooth muscle (and serosal) tissue and scraped epithelial cells and rat (n = 2) bladder muscle (and serosal) tissue and scraped epithelial cells. B: ROMK signal was ablated when ROMK antibody was preabsorbed with its immunizing peptide. C: immunoblot using chicken antibody to ROMK is homogenates of rat whole bladder, bladder muscle, and bladder epithelia. D: immmunoblot using antibody to calponin, a marker of smooth muscle cells, in the same nitrocellulose membrane used in C. Calponin was not identified in the epithelial cell scrapings. BW, whole bladder; BM, bladder muscle; BE, bladder epithelial cells.