Abstract
The epithelium of the main excretory duct of the rat submaxillary gland was used as a target tissue for studies on the effect of a spironolactone on electrolyte transport. The spironolactone decreased net Na+ reabsorption by 27% and net K+ secretion by 23%. HCO-3 was found to be about 2-fold accumulated in the duct lumen, which was considered to result from decreased H+ion secretion. The results can be reconciled with an action of spironolactone on 1) the peritubular Na+-K+-exchange mechanism and 2) the functional coupling of Na+ entry from lumen to cell with K+ and H+ transfer from cell to lumen.