On the Mechanism of Glucose Absorption from the Intestinal Tract.

Abstract

Pierce and collaborators 1 recently published 2 statements: (1) The rate of absorption of glucose falls off during the last hour of a 3 hour period. This, they say, does not agree with Cori's findings. (2) The percentage of glucose absorbed during 1, 2 and 3 hour periods depends upon the amount of glucose remaining unabsorbed in the alimentary tract. The experimental data on which these 2 statements rest, appeared simultaneously elsewhere. 2

The decrease in the rate of absorption in the third hour is not difficult to explain, because Pierce did not feed enough sugar to let the absorption proceed for 3 hours. Whereas an average of 236 mg. of sugar was absorbed in the first hour and of 229 mg. in the second hour, only 88 mg. of sugar were available for absorption in the third hour. Pierce erroneously assumed that absorption was not completed after 3 hours, because he made no allowance for the blank (sugar plus non-sugar reducing substances) given by empty intestines. In our experiments 3 an average of 235 mg. of glucose remained unabsorbed in the intestine after 3 hours. In this case the blank can be neglected, because it constitutes only a small percentage of the sugar content of the intestine, especially if the determinations are made with the less sensitive Bertrand method. In the experiments of Pierce there remained an average of only 44 mg. of sugar per 100 gm. rat. In 4 individual experiments 24, 10, 24, and 18 mg. of sugar per 100 gm. rat were found remaining in the intestine. This corresponds to an absorption of 95.5 to 97.7% of the sugar fed, which is evidently complete absorption, considering that Pierce used the Folin-Wu method∗ and made no allowance for the rather high blank which this method gives for intestines of fasting rats.