THE INFLUENCE OF DIET ON THE SUSCEPTIBILITY OF RATS TO ALPHA-NAPHTHYLTHIOUREA

¹ University of Chicago Toxicity Laboratory; Department of Pharmacology, University of Chicago, Chicago, Illinois

1. Variations in the fat, carbohydrate, and protein, within limits which provided normal or nearly normal growth of rats, did not alter the resistance of rats to ANTU poisoning. Lowering the protein content of the diet to 6% or 0% slightly increased the susceptibility to ANTU.

2. A diet high in cystine provided rats with some protection against ANTU poisoning when the diet was fed for 10 days. If the same diet was fed for longer periods, however, the protective action of cystine was lost until at 30 days no protection remained. It was necessary to provide enough choline in the diet to give normal growth before cystine increased the resistance to ANTU.

3. Potassium iodide or Lugol's solution fed either in the drinking water or in the diet protected rats against large doses of ANTU. Potassium iodide fed at a level of 5.7 mgm. per gram of diet for 10 days provided rats with enough resistance to survive doses of ANTU as high as 100 mgm./kgm.

4. A diet containing 5.7 mgm. of iodine/gram provided thyroidectomized rats with much less protection than it did normal animals against ANTU.

5. The intravenous injection of iodine as diluted Lugol's solution immediately before the administration of ANTU resulted in no observable protection against the rodenticide.

6. A diet containing 12.5 mgm. of desiccated thyroid per gram fed for a 2-day period offered no protection to rats against ANTU.