[New concepts of nephron function and the mechanisms of action of diuretics].

The hypothesis of gate charges of intracellular junctions of nephron wall is proposed. According to the hypothesis, negative charges at the entrance of the channel fixed on the lumenal side of nephron epithelium permit cation entry and block anion flow in the channel. The interaction of ions and fixed charges with sodium leads to increased reabsorption of various cations including sodium and also enhanced excretion of chloride and hydrogen ions in the urine resulting from osmotic fluid and ion diffusion through intracellular junctions. Mercurial diuretics, ethacrynic acid and osmotic agents but not furosemide enhance permeability of intracellular junctions for ions and eliminate the selective function of the fixed charges.