INHIBITOR EFFECTS ON THE IONIC EXCHANGES THROUGH THE HUMAN AMNIOTIC EPITHELIAL-CELL MEMBRANES

Direct measurements of cell podocyte/or microvillous membrane ionic ex changes were performed on the membranes of isolated human amniotic epi thelial cells. The ionic exchanges were determined from the measures o f cellular input conductances. The effects of various inhibitors: ouab ain, amiloride, -acetamido-4'-isothiocyanostilbene-2,2'-disulfonic aci d (SITS), 4'4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), qui nidine, barium, manganese were analyzed. This study shows that the ion ic exchanges through the epithelial cells are regulated by the presenc e of Na+, K+, Cl- channels, Na+/H+-Cl-/HCO3- antiports, (Na-K)ATPase a nd Na+/ Ca2+-Na+/Mg2+ exchangers on the 2 faces of the cells and of a Na+-K+-2Cl(-) cotransport on the membrane facing the amniotic cavity o nly.