It has been reported that vasopressin (AVP)-sensitive renal epithelial cell line (MDCK) forms morphologically polarized monolayers when cultured on plates. We studied whether the AVP-responsive cAMP production system would be located solely on the basolateral surface of these cells as has already been shown on the renal tubules. We used two methods to overcome the inaccessibility to the basolateral surface of the cultured cell layer and to study the apical and basolateral surfaces separately. One was culture on collagen sheet and the other was on Millipore filters. Our experiments showed that MDCK cell increased adenosine 3': 5'-cyclic monophosphate (cAMP) content prominently only when vasopressin was accessible to the basolateral surface.
Accordingly, MDCK cells were shown to have the AVP-responsive cAMP production system predominantly on the basolateral surface of the cell membrane.