ELECTROLYTE HOMEOSTASIS IN UROTHELIAL NEOPLASIA - THE EFFECTS OF AMILORIDE

Objective To investigate the effect of amiloride preincubation on the intracellular electrolyte levels in neoplastic and non-neoplastic urot helium. Materials and methods Samples of papillary transitional cell c arcinomas (grades 1 and 2) and non-neoplastic human urothelium were ei ther frozen immediately or after pre-incubation with Krebs saline alon e or with Krebs saline containing amiloride, The frozen samples were p laned in a cryo-ultramicrotome and then examined by low temperature sc anning electron microscopy. Intracellular electrolyte levels were meas ured using X-ray microanalysis. Results In the cells frozen immediatel y the ratios K+/Na+, K+/P and K+/Cl- were significantly increased in n eoplastic compared with non-neoplastic urothelial cells (P<0.001). Thi s difference was also found in the cells pre-incubated with Krebs sali ne alone but was not present in the cells pre-incubated with amiloride . Conclusions These results were consistent with the concept that acti vation of the amiloride-sensitive Na+/H+ membrane exchanger is a prima ry event in neoplasia.