title: Studies of the tolerance and disposition of ochratoxin A in young calves.
abstract: Tolerance to and disposition of ochratoxin A (OA) were compared in preruminant and ruminant calves. Two preruminant calves receiving 4.0 mg OA/kg body weight by stomach tube died; one of two calves receiving 1.0 mg/kg body weight survived. At a dose of .5 mg OA/kg body weight both calves survived. The administered OA was converted mainly (80.1 to 88.9%) to ochratoxin-alpha (O alpha), which was found only in urine; the remaining OA appeared in the urine (3.2 to 3.3%) and feces (7.8 to 10.0%). In the one surviving calf of two given .25 mg OA/kg body weight i.v., nearly twice as much OA was excreted in the feces (44.5%) as in the urine (25.0%); no O alpha was found in urine or feces. All four calves with functional rumens receiving OA orally, 2.0 mg/kg body weight, survived without overt ill effects. Approximately 90% of the OA was excreted as O alpha, with approximately four to eight times more in the urine than in the feces; OA was low in the urine or feces. A plot of the serum OA concentration-time data revealed a prominent, sustained, secondary peak, which was described adequately by a four-exponential equation with two apparent absorption components. Accordingly, OA initially was absorbed rapidly by a first-order rate process (ka = .496/h), and following a considerable delay (tlag = 12.84 h) absorption appeared to resume by a second, slower, first-order rate process (ka = .127/h). The second absorption phase was best explained as being due to enterohepatic cycling of OA.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: University of Manitoba, Winnipeg, Canada.
authors.forename: O
authors.initials: O
authors.lastname: Sreemannarayana
authors.forename: A A
authors.initials: AA
authors.lastname: Frohlich
authors.forename: T G
authors.initials: TG
authors.lastname: Vitti
authors.forename: R R
authors.initials: RR
authors.lastname: Marquardt
authors.forename: D
authors.initials: D
authors.lastname: Abramson
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004361:Drug Tolerance; D007262:Infusions, Intravenous; D008297:Male; D009793:Ochratoxins / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000633:toxicity
chemical_list: D009793:Ochratoxins; C025589:ochratoxin A