Avian diuretic response to renal portal infusions of the mycotoxin citrinin.

Citrinin is a nephrotoxic mycotoxin produced by common molds. Previous research has shown that citrinin causes increased urine flow, increased free water clearance, and increased sodium, potassium, and inorganic phosphate excretion. The present study was conducted to evaluate the dose-response effects of citrinin and to further evaluate previously reported phosphaturic effects of citrinin. Ureteral urine was collected from anesthetized domestic fowl during a control period (30 min) and during unilateral renal portal infusion (90 min) of citrinin carrier vehicle, 200 ppm citrinin, or 400 ppm citrinin. Comparisons of the portal infused vs. uninfused kidneys were used to evaluate the direct effects of citrinin. Citrinin caused acute (unilateral) dose-related increases in urine flow, free water clearance, and fractional sodium excretion and dose-related decreases in urine osmolality. Citrinin had no direct effect on glomerular filtration rates, fractional potassium excretion, or fractional inorganic phosphate excretion. An additional group of birds received systemic intravenous infusions of parathyroid hormone (PTH) beginning 40 min after the start of unilateral renal portal infusion of citrinin. The citrinin and PTH infusion were continued for 60 min. Fractional inorganic phosphate excretion increased bilaterally during the citrinin-PTH infusion period but citrinin had no direct phosphaturic effect. Previously reported phosphaturic effects of citrinin were not confirmed in the present study.