[Furosemide-sensitive transport of chloride through the apical membrane of cells of the proximal tubule of the triton kidney].

The effect of furosemide on transtubular electrical potential (Vt) as well as on the potentials of apical (Va) and basolateral (Vb) membranes of the Triturus vulgaris proximal nephron cells was studied in alteration of the electrochemical potential gradient Na+ and Cl- through the apical membrane. Furosemide did not change the Va and Vb provided the concentration of NaCl in the lumen of proximal canal was the same as in the blood plasma. When the NaCl concentration diminished in the lumen furosemide increased Va and Vb, the Vt remaining unchanged. The effect of furosemide is considerably lesser when the Cl- concentration alone diminishes in the lumen. The data obtained suggest presence of furosemide-sensitive transport of Cl- in the apical membrane of proximal canal cells in the Triturus kidney. This membrane seems to have systems of electrogenic transport of Cl- insensitive to furosemide but depending on the Na+ electrochemical potential gradient.