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SOME EFFECTS OF THE INTRAVENOUS INJECTION OF CORN GLYCOGEN INTO RABBITS* BY DANIEL LUZON MORRIS (From the Putnell School, Putney, Vermont) (Received for publication, March 2, 1943) Although glycogen has long been recognized as the chief form in which carbohydrates are stored in the animal body, it has been chemically a comparative rarity. Despite its importance and almost universal oc- currence, relatively few physiological experiments with the substance itself have been recorded, and the simple consideration of price has pre- vented any possibility of its clinical use. Recently a polysaccharide has been isolated from sweet corn (Zea mays), the properties of which seem to agree throughout with those of animal glycogen (1,2). The concentration of the material in corn is high, being of the order of one-eighth of the dry weight of the grain, and it is rather easily obtainable in a high state of purity, possibly more nearly nitrogen-free than animal glycogen can be prepared (3). Physiological investigation of this material seemed urgently indicated, with the practical possibility of clinical use in mind. Glycogen has certain properties unique among chemical compounds. Like starch and cellulose, it has a high molecular weight; recent estimates are in the neighborhood of 2 million. But, unlike these polysaccharides, it is highly soluble in water, and shows no tendency to precipitate or “retro- grade” with time. The molecule is composed of nothing but glucose units, linked in the a! configuration, and is readily broken down, at least to half it,s original size (4), by the diastases which are present in nearly every living cell. The immediate breakdown products are dextrins, maltose, and glu- cose, and the dextrins and maltose may be further degraded to glucose. These properties make it desirable to consider the possibility of injecting glycogen directly into the blood stream. The molecule is so large that diffusion of the unchanged substance through the walls of the blood vessels would be slow. There is an active diastase in blood, which will break down glycogen more or less rapidly to set free glucose. And finally, gly- cogen as a physiological constituent of the body is presumably non-toxic. In any case it has been claimed to be present in small amounts in normal blood (e.g. (5)), though some workers have doubted that the polysac- charide in blood is actually glycogen (6). Staub and his coworkers have conducted extensive studies both on normal blood glycogen levels and on the effects of intravenously injected * Aided by a grant from Mead Johnson and Company. 699 by guest on March 23, 2016 http://www.jbc.org/ Downloaded from