Study of enzymes regulating vasopressin-stimulated cyclic AMP metabolism in separated mitochondria-rich and granular epithelial cells of toad urinary bladder.

The epithelial cells of the toad urinary bladder are morphologically heterogenous. In order to relate the effect of vasopressin on cyclic AMP metabolism to cell type, the epithelial cells were separated by the density gradient technique of Scott, Sapirstein and Yoder (Science 184:797, 1974). The separation was verified by electron-microscopy and by observing that the band of cells enriched in mitochondria-rich cells was enriched in carbonic anhydrase activity compared to the band of granular cells. A large portion of cells collected from the gradient was considered to be nonviable, precluding further study of their function as intact cells. Vasopressin-stimulated adenylate cyclase activity in homogenates of granular cells was simular to that in homogenates of mitochondria-rich cells. Cyclic nucleotide phosphodiesterase activity was also similar in the two types of cell. Thus, the enzymes known to be involved in cyclic AMP metabolism in response to vasopressin appear to be located in both major cell types.