On the nature of the action of vegetable extracts on the blood sugar of normal rabbits

The recent work of Winter and Smith 1 , Best and Scott 2 , Funk and Corbitt 3 , and of Collip 4 establishes the point that there is present in yeast and in plants and vegetables a substance which, upon injection into normal rabbits, causes a fall in blood-sugar. In this connection, the experiments of Thalhimer and Perry, 5 and Fetzer 6 led to similar observations. Best and Scott, working with extracts of potatoes and rice, obtained results like those following an injection of insulin. On the other hand, Funk and Corbitt (unpublished data), as well as Collip, observed from their experiments with various vegetable extracts that there was usually a preliminary hyperglycemia and that the blood-sugar reducing effect did not manifest itself until some time after the injection. They found also that the effect was more prolonged than was the case with insulin. Because of this delayed and prolonged action, the above investigators conclude that the blood-sugar reducing substance present in vegetables— “Glucokinin,” as Collip calls it—is not identical with insulin. The results of the present work tend to show that the blood-sugar reducing substance obtained from vegetable sources, if freed from the hyperglycemia-producing principle, behaves in a manner similar to that exhibited by insulin. Detailed data will shortly be published elsewhere; for the present, we may summarize briefly as follows : 1. It appears that yeasts and vegetables such as cabbage, celery, lettuce, etc., contain both blood-sugar increasing and blood-sugar decreasing substances. 2. Crude extracts, when injected, may produce either a rise in blood-sugar or a rise followed by a fall below the normal. 3. The same effect may be produced by the injection of l-suprarenin bitartrate (synthetic). 4. In one experiment, 6 cc. of whole blood of a normal rabbit injected into another normal rabbit resulted in a 20 per cent decrease in bloold-sugar in 54 hours. Two other experiments gave doubtful results. These experiments were undertaken to satisfy ourselves as to the effect of the injection of normal blood. They are not intended to disprove Collip's statement as to the animal passage of a hypoglycemia-producing substance. 5. On fractionating crude extracts, it is possible to separate almost entirely the hyperglycemic from the hypoglycemic substance. 6. The preliminary fractionation is effected with allcohol; the finall separation involves the use of dinitrosalicylic or picric acid. Working with pancreas, Dudley 7 also used picric acid for this purpose.