Parenteral supply of vitamin A to sheep

Abstract

A total of 20 sheep was used to study the effect of intramuscular injections of four different doses of vitamin A. One group received the vehicle only (control group), while the others were injected i.m. with vitamin A. Group 2: 1.5 × 10 6 IU, Group 3: 3 × 10 6 IU and Group 4: 5 × 10 6 IU. There was an increase in plasma vitamin A with increase in vitamin A injection. Sheep injected with 5.0 × 10 6 IU vitamin A had significantly higher plasma vitamin A concentrations than control sheep. The area under the plasma concentration curve (AUC) tended to increase with higher doses of vitamin A injection, and the greatest AUC was observed in sheep with 5 × 10 6 IU of vitamin A. Some proportionality between vitamin A dose given and tissue vitamin A concentration was found, with the liver containing the highest concentration within tissues. This organ is the most reliable index of vitamin A body storage. Linear regressions of log tissue concentrations on plasma concentrations were mostly not significant except for adrenal, and the slope ranged from −0.24 to 0.69. The results showed that parenteral administrations of high (5.0 × 10 6 IU) doses of vitamin A in sheep increase significantly the concentrations of this vitamin in liver and caution should be taken on the consumption of liver by humans.