CHARACTERIZATION OF HORMONE-STIMULATED NA-RESISTANCE CLONE OF THE MDCK CELL-LINE( TRANSPORT IN A HIGH)

The Madin-Darby canine kidney (MDCK) cell line forms an epithelial mon olayer which expresses many of the morphological and functional proper ties of the renal collecting duct. The C7 subclone of the parent line forms an epithelium which expresses many of the characteristics of pri ncipal cells. The MDCK-C7 subclone forms a high-resistance epithelium that is capable of vectorial ion transport, We have found that this ep ithelium responds to aldosterone, antidiuretic hormone (ADH) and insul in like growth factor 1 (IGF1) with increases in amiloride-sensitive N a+ transport. The responses to aldosterone and ADH follow time-courses that are consistent with the action of these hormones in vivo, This i s the first demonstration of IGF1-induced Naf reabsorption in a mammal ian model system. Interestingly, a maximal response to ally one of the se natriferic factors does not inhibit a subsequent response to anothe r hormone. These studies indicate that the C7 subclone retains many of the natriferic responses of the native principal cells and is an idea l model for studying hormonal modulation of Na+ transport.