Localization of amiloride-sensitive sodium channels in A6 cells by atomic force microscopy
Smith, P.R.; Bradford, A.L.; Schneider, S.; Benos, D.J.; Geibel, J.P.
American Journal of Physiology 272(4 Pt 1): C1295-C1298
1997
ISSN/ISBN: 0002-9513 PMID: 9142855 Document Number: 472064
Atomic force microscopy (AFM) was used for high-resolution imaging of the apical distribution of epithelial Na I channels in A6 renal epithelial cells. A6 cells grown on coverslips were labeled with antibodies generated against an amiloride-sensitive epithelial Na+ channel complex purified from bovine renal medulla that had been conjugated to 8-nm colloidal gold particles before preparation for AFM. AFM revealed that there was a marked increase in the height of the microvilli in cells labeled with the anti-epithelial Na+ channel antibodies compared with unlabeled cells or cells labeled with rabbit nonimmune immunoglobulin G conjugated to colloidal gold particles. We interpret this apparent increase in microvillar height to be due to anti-epithelial Na+ channel antibody binding to the apical microvilli. These data demonstrate that epithelial Na+ channels are restricted to the apical microvilli in Na+-transporting renal epithelial cells. Furthermore, they demonstrate the applicability of using AFM for high-resolution imaging of the cell surface distribution of epithelial ion channels.