Glycocoll nitrogen in the metabolism of the dog

Abstract

While attempting to explain the behavior of gelatin in metabolism it occurred to the writer that much significance might be attributed to its high content of glycocoll. It is well known that the nitrogen of gelatin is not ordinarily retained in the body but appears quantitatively in the urine, chiefly as urea. But when fed with meat and abundance of carbohydrate it is possible to establish nitrogen equilibrium near the fasting level, if two-thirds of the total quantity of nitrogen fed is present in proteid-free gelatin and only one-third present in the meat. 1 Would glycocoll, if fed in the same way, behave as does gelatin?

v. Brügsch and Hirsch fed 20 gm. of glycocoll 1 to a fasting woman on the twelfth day of her fast and observed that all of its nitrogen appeared in the urine as urea. Samuely 2 had likewise observed this fate (chiefly) of glycocoll nitrogen when glycocoll was added to meat and other foodstuffs in the diet of dogs suffering from artificial anemia. But Lüthje 3 reports a nitrogen retention, with asparagin and glycocoll as the only sources of nitrogen, provided carbohydrates are fed freely at the same time. He thinks there may be a synthesis of the amino acids with carbohydrate and the formation of an “amino sugar,” which escapes the destructive processes of the body.

It has appeared in my experiments with gelatin that the power of the body to conserve its nitrogen supply is stronger the lower the proteid condition of the animal at the time of feeding. For the purpose of testing the power of retaining glycocoll nitrogen therefore, I prepared the dogs by subjecting them to long periods of fasting or under-nutrition.