INCREASE OF RESISTANCE TO OXYGEN WANT IN ANIMALS ON CERTAIN DIETS

¹ National Institute for Medical Research, Hampstead

1. Compared with the normal diet, a pure carrot diet gives definite protection against acute oxygen want, in the case of the animals tested (rats, mice).

2. A synthetic non-protein diet with almost no fat and containing rice-starch 70•5 per cent., yeast 3 per cent., salts 1•5 per cent., and 25 per cent. of cellulose gives some similar protection. If the cellulose is replaced by a similar percentage of kaolin or agar no protection is gained. The cellulose action therefore does not appear to be mechanical or merely adsorptive.

3. Proteins enhance the effects of oxygen want, opposing the action of carrots. Specific dynamic action or toxic unoxidised by-products may be concerned.

4. The protection given by carrots is not due entirely to their low protein, low fat, and cellulose content, since carrots give much better protection than parsnips which also have similar low percentages of protein and fat. Also the cellulose content of the parsnips consumed is similar in absolute quantity to that in the carrot consumed.

5. Carrots must either contain an extra substance which opposes the effects of oxygen want or they must lack some factor or factors which enhance oxygen want. Boiling for 15 minutes does not lower the protective power of the carrots. Similar diets with adequate carbohydrate, salts, and vitamins might be given a trial for patients with oxygen want. Body-weight and vigour seem to be fairly well maintained on such a diet for at least a week in rats.

6. It is possible that a detoxicating action in the intestine or elsewhere may play some part in the protection, and the anærobic fermentation of cellulose may also be indirectly concerned.

I am indebted to Sir Robert Davis for facilities at Messrs. Siebe Gorman's premises, S.E.1; also to my colleagues, Dr. C. Rimington, Mr. T. A. Webster, and Mr. H. P. Marks, for some co-operation, information re diet, and the estimations of liver glycogen respectively. Dr. O. Guggenheim of Basle kindly provided the sample of lactoflavin.