Alkalinization of urinary pH accelerates renal excretion of ochratoxin A in pigs

The mycotoxin ochratoxin A (OA) is a cause of endemic nephropathy in farm animals and humans. Reabsorption of OA along the nephron results from nonionic diffusion and by carrier-mediated mechanisms, indicating that urine alkalinization may help to accelerate OA excretion and thus reduce its toxicity. The aim of the present study was to investigate the effect of a dietary sodium bicarbonate supplementation as a means of increasing urinary pH on the systemic availability and excretion of OA in pigs. Dietary supplementation of 2% sodium bicarbonate significantly increased urinary pH (5.7 +/- 0.2 to 8.3 +/- 0.1) and daily urine volume (1108 +/- 276 to 2479 +/- 912 mL). The systemic availability of OA and its dechloro-analog, Ochratoxin B (OB), calculated as the area under the curve (AUC) was reduced to 75 and 68%, respectively, of the control group (P < 0.05). This effect was due mainly to an accelerated elimination of OA and OB in the urine. The faster renal elimination may be due to reduced reabsorption of the ochratoxins by nonionic diffusion, and other H(+)-dependent mechanisms. Thus, urinary alkalinization may be an efficient means to partially reduce the toxic effects of OA in pigs.