Fumonisin B-1 increases serum sphinganine concentration but does not alterserum sphingosine concentration or induce cardiovascular changes in milk-fed calves

Fumonisin B-1 is the most toxic and commonly occurring form of a group of m ycotoxins that alter sphingolipid biosynthesis and induce leukoencephalomal acia in horses and pulmonary edema in pigs. Purified fumonisin B-1 (1 mg/kg , iv, daily) increased serum sphinganine and sphingosine concentrations and decreased cardiovascular function in pigs within 5 days. We therefore exam ined whether the same dosage schedule of fumonisin B-1 produced a similar e ffect in calves. Ten milk-fed male Holstein calves were instrumented to obt ain blood and cardiovascular measurements. Treated calves (n = 5) were admi nistered purified fumonisin B-1 at 1 mg/kg, iv, daily for 7 days and contro ls (n = 5) were administered 10 ml 0.9% NaCl, iv, daily. Each calf was euth anized on day 7. In treated calves, serum sphinganine concentration increas ed from day 3 onward (day 7, 0.237 +/- 0.388 mu mol/l; baseline, 0.010 +/- 0.007 mu mol/l; mean +/- SD), whereas, serum sphingosine concentration was unchanged (day 7, 0.044 +/- 0.065 mu mol/l; baseline, 0.021 +/- 0.025 mu mo l/l). Heart rate, cardiac output, stroke volume, mean arterial pressure, me an pulmonary artery pressure, pulmonary artery wedge pressure, central veno us pressure, plasma volume, base-apex electrocardiogram, arterial Po,, and systemic oxygen delivery were unchanged in treated and control calves. Fumo nisin-treated calves developed metabolic acidosis (arterial blood pH, 7.27 +/- 0.11; base excess, -9.1 +/- 7.6 mEq/l), but all survived for 7 days. We conclude that calves are more resistant to fumonisin B-1 cardiovascular to xicity than pigs.