THE UTILIZATION OF SUGAR Ml 



relative quantities of II ami OH ions, of available oxyKen, salts, etc.. found in the 

 various phases of the cell. This conception is based on that used by Nef to ex- 

 plain the behavior of sugars in alkaline solutions. For a concrete conception of 

 the dynamics of a reaction between an organic substrate and catalyst the reader 

 is referred to Van Slyke's study of the enzyme urea.sc.' 



The general principles outlined above may he illustrated by experi- 

 ments with timed intravenous injections of glucose. It has long been 

 kno\vn that if a comparatively large dose of glucose is injected rapidly 

 into a peripheral vein a marked glycosuria usually results. Pavy, 

 however, emphasized the fact that a material fraction of a dose so 

 given fails to be excreted and appears to be utilized. Doyon and 

 Du Fourt demonstrated that with a standard dose of glucose the i)er- 

 centages excreted and utihzed respectively are influenced by the time 

 consumed in injection, the slower rates of injection causing lower per- 

 centage excretions and vice versa. Blumenthal chose a standard in- 

 jection time of about 10 seconds and varied the weight of sugar given 

 in that time. He found that a certain dose of glucose might be 

 injected into the ear vein of a rabbit without causing any glycosuria 

 at all. However, the maximum dose which could be so injected once 

 could not be repeated 15 minutes later without causing glycosuria. 

 He assumed from this that the first dose "saturated" the tissues and 

 that fifteen minutes later the utilization of sugar had only resulted in 

 a partial desaturation. He, therefore, determined the dose of glucose 

 which might be injected repeatedly at 15 minute intervals for as long 

 as 3 hours without ever causing glycosuria. His figures varied be- 

 tween 0.6 and 1.3 gm. per kg. of body weight per hour. This he 

 termed the "utilization limit," whereas the largest dose which could 

 be given within 10 seconds once without causing glycosuria he called 

 the "saturation limit." The latter he placed at 0.8 gm. per kg. but 

 R. M. Wilder has been unable to confirm this latter observation. 

 Woodyatt, Sansum and Wilder^ made continued intravenous injections 

 of glucose at uniform rates by means of a motor driven pump for 2 to 

 17 hours with the following findings: 



If chemically pure glucose in aqueous solution is injected con- 

 tinuously into the peripheral venous blood of a normal resting man, 

 dog or rabbit at the rate of 0.8 gm. per kg. of body weight per hour, 

 or at any slower rate, the injection may be sustained in most cases, 

 hour after hour for 7 hours and probably longer without producing 

 any glycosuria in the usual sense of the word. If the rate is advanced 

 to 0.9 gm. of glucose per kg. of body weight per hour, while all other 

 conditions remain the same, the injection may be sustained for a short 

 time without causing glycosuria, but in nearly all cases abnormal 

 quantities of glucose begin to appear in the urine after 5 to 30 minutes 



8 Jour. Biol. Chem., 1914 (19), 141. 



9 Jour. Amer. Med. Assoc, 1915 (G5), 2067 (preliminary report); \\oodyatt, 

 Harvey Society Lectures, 191G; Wilder and Sansum, Arch. Int. Med., 1917 (19), 

 311; Woodyatt and Sansum, Jour. Biol. Chem., 1917 (;30), 155. 



