Apical surface and cytoskeleton of epithelial monolayers from the A6 kidney cell culture line

To evaluate possible morphological alterations paralleling functional studi es on the role of the cytoskeleton in ion transport processes, the kidney e pithelial cell line A6, derived from Xenopus laevis, was examined by scanni ng electron microscopy and fluorescence microscopy. Microridges and cell sh ape, as well as microtubule and actin filaments, undergo profound alteratio n if exposed to colchicine, cytochalasin D, EHNA (erythro-9-(2-hydroxy-3-no nyl) adenine hydrochloride), and hypoosmotic shock in a cell density-depend ent manner. While confluent cell layers treated with EHNA or colchicine sho wed no differences detectable by the methods used to control cell layers, c ytochalasin D treated cell layers expressed less microridges on the apical surface as well as less basal stressfibres. Hypoosmotic stressed cells show ed more basal stressfibres than control layers. Subconfluent cells exposed to colchicine or EHNA, however, also express an apical addition of surface structures and, compared to control cells, more cells are spherical, whilst microtubules are only disrupted if cells were exposed to colchicine. This study shows that profound morphological alterations result after the applic ation of cytoskeleton blockers, and should not be neglected in functional s tudies. The significance of the alterations found to electrophysiological e xperiments is discussed.