ION-TRANSPORT BY HUMAN ENDOMETRIAL EPITHELIA IN-VITRO

Human glandular endometrial epithelial cells were cultured on porous t issue culture inserts to form tight, confluent layers. These layers ge nerated time-dependent modifications in the ionic composition of both apical and basolateral solutions. Increases in sodium and chloride con centrations in the basolateral fluid were accompanied by reciprocal de creases in the concentrations of these ions in the apical fluid. The p otassium concentration was increased in the apical, while decreased in the basolateral, solution. The total calcium concentration was slight ly elevated in the apical, as compared with the basolateral fluid, whi le there were no alterations in pH. The endometrial layers demonstrate d a significant trans-epithelial potential difference, and when this v alue was substituted in the Nernst equation a prediction of the passiv e distribution of ions across the cells was possible, indicating that none of the ions were in equilibrium. Addition of the sodium channel b locker amiloride to the medium bathing the cell layers reduced the mod ifications in ionic composition of apical and basolateral solutions. T he data are consistent with other data indicating an amiloride-sensiti ve sodium-absorptive function for the endometrial epithelium. The abil ity of these primary cultures of endometrial epithelial cells to reduc e the sodium while increasing the potassium concentration of the apica l fluid is qualitatively in agreement with the low sodium and high pot assium concentrations reported for human uterine fluid. The data sugge st a role for the endometrial epithelium in generating and maintaining the distinctive ionic composition of the intra-uterine environment.