RESUMO
To determine the effect of gentamicin on the functional properties of the glomerular barrier, 44 Wistar rats received daily doses of 80 mg/kg body weight for 6 days. Glomerular permeability to neural dextrans and albumin was evaluated by day 6 and albuminuria was determined on the 1st, 3rd and 5th days of treatment. Treatment induced an intense increase in albuminuria from 74 ug/24 h to 11.5 mg/24 h on the 5th day of treatment (N=11). This increase was associated with the presence of large amounts of albumin in elements of the glomerular filter and in the apical region of the proximal tubular cells (N=4). Fractional clearances of neutral dextrans having molecular radii in the range of 18-41 A were not significantly different in control (N=5) and gentamicin-treated rats (N=7). These results show that gentamicin, a polycation at pH 7.4, produces an increase in the glomerular permeability to negatively charged macromolecules in rats, probably due to interaction of the polycation with negative charges in the glomerular filter