Six groups of rats on different diets were exposed to the inhalation of carbon tetrachloride (about 300 p. p. m.) for 150 days. Food intake and changes in weight were followed throughout the experiment. Animals fed a diet low in protein showed greater susceptibility than rats on a diet high in protein. Methionine was a good substitute for protein (casein) in the diet. Increase in fat intake with correspondingly lower carbohydrate intake exerted a harmful effect, especially evident in combination with a low protein diet. In this change of the fat: carbohydrate ratio, whether the increased fat or the lowered carbohydrate is the specific factor must remain unanswered at the present time.
Necrotizing nephrosis was the presenting sign of the intoxication caused by carbon tetrachloride, in addition to hepatic changes, such as hydropic degeneration, necrosis, and cirrhosis. Dietary factors (methionine and methionine-containing protein, as well as low fat intake) more consistently prevented renal injury than cirrhosis of the liver.
Under identical dietary conditions, especially with higher fat intake, male rats appeared to evince greater susceptibility to carbon tetrachloride than female rats. The significance of this observation and its wider applicability has been discussed.