Pharmacology and toxicology of carbon tetrachloride in the sheep. IV. Reduction and augmentation of toxicity by selenium

Abstract

Susceptibility of sheep to toxic effects of carbon tetrachloride (CCl₄) was assessed by determining the increase in plasma levels of isocitric dehydrogenase (ICD) and glutamic transaminase (GOT) and by other criteria.

Susceptibility was increased by oral administration of 1 mg of selenium (Se) as sodium selenite plus 100 i.u. of tocopherol acetate on alternate days for 120 days, 2 mg Se per day for 21 days, and 6 mg Se per day for 6 days, before dosing with CCl₄. Susceptibility was reduced by smaller total amounts of Se, and by oral doses of 6 mg Se per day for 3 days, a single oral or intramuscular dose of 5 or 12 mg c. 20 hr, or 5 or 12 mg orally 10–20 min, before dosing with CCl₄. One 5 mg dose at 20 hr and a second 20 min before CCl₄ was more effective than either alone.

Sheep from two different sources differed considerably in their susceptibility to CCl₄. In the more susceptible sheep Se administration reduced susceptibility to a level comparable with that shown by the naturally resistant animals.

Administration of Se to sheep dosed with CCl₄ and then given a high-protein diet resulted in lower GOT levels, milder clinical signs, and a great reduction in mortality.

In field tests on properties with a recent history of CCl₄ poisoning, oral administration of 5 mg Se about 20 min before CCl₄ significantly reduced susceptibility.

Administration of Se to fluke-infested sheep did not protect the liver fluke (Fasciola hepatica) against CCl₄.