A note on the parenteral administration of starch

Very little work has been done on the question of the production of a protective amylase after the parenteral administration of starch. Most observers agree that the blood normally contains a starch-splitting enzyme. There is also abundant evidence that the term amylase is applied to a variety of starch-splitting enzymes characterized chiefly by the extent of the hydrolysis, such as the production of soluble starch, dextrins, and reducing sugars. We have found that the blood of a given animal may vary considerably from day to day, sometimes producing dextrins slowly and reducing sugars rapidly, or dextrins rapidly and reducing sugars slowly. It is evident that the study of the formation of a protective amylase after parenteral introduction of starch calls for a quantitative study of at least three phases of starch hydrolysis.

We have at hand data on seven dogs. These animals have received both single and repeated intravenous injections of soluble starch. No constant or significant increase in the amylolytic activity of the blood has been found, There is, however, a great increase in the amylolytic power of the urine on the day following the injection of the starch, the increase being shown by a more rapid production of both dextrins and of reducing sugars.

In the interpretation of these results it appears possible that there is an increased production of amylase after the injection of starch, but the kidneys eliminate it so rapidly that there never is present in the blood enough of the excess over the normal to be detected by any of our present methods. On the other hand the amylase may be present in the blood in an inactive state, perhaps in combination with some colloid, and on the introduction of a suitable substrate this combination is broken up, and at least a part of the enzyme eliminated by the kidneys before it can recombine.