Tubular effects of acetaminophen in the isolated perfused rat kidney.

The effects of different acetaminophen (APAP) concentrations (1, 5 or 10 mM) on renal function were investigated in the isolated perfused rat kidney (IPK). APAP was added to the perfusion media as a single dose after a equilibration time and control periods. Changes in fractional excretion of sodium (FENa), water (FEH2O), glucose (FEglu) and in glomerular filtration rate (GFR) were measured. The lower concentration used only modified the FEH2O. APAP 10 mM induced an increment in FEH2O (72% higher than control preparation), FENa (79% higher than control preparation) and an elevation in glucose excretion (55% higher than control preparation), associated with a decrease in GFR (23% lower than control preparation). The influence of PGE2 on the effects of APAP was also investigated. PGE2 prevented the APAP-induced decrease in GFR and in glucose reabsorption, but did not change the pattern of sodium and water handling. The effects of another vasodilator, verapamil, on APAP-induced renal effects were also tested. Verapamil prevented the glomerular but not the tubular effects of APAP. Urinary APAP excretion data showed a similar availability of APAP to the tubular cells in all the groups. Our data suggest that APAP exerts a direct action in the IPK, affecting hemodynamic and tubular functions, and that the latter are not a consequence of hemodynamic alterations.