The formation of urea in autolysis.

Abstract

As a result of the recent experiments of Bollman, Mann and Magath 1 there is now little doubt that the liver plays the leading rôle in urea formation. Nevertheless very little is known concerning the mechanism of urea formation. To be sure we have long known from the experiments of Kossel and Dakin 2 that argininie may be split directly into urea and ornithine under the action of a specific enzyme, arginase, but relatively this accounts for only a small amount of the urea formed.

We wish to record observations of autolysis experiments carried out some years ago 3 (1914) which we have recently confirmed and extended 4 . The original motive for initiating these experiments was the availability of a specific method for estimating urea (Marshall). We were able to show then that whereas urea formation took place in autolyzing liver tissue, no change in the concentration of urea occurred in muscle tissue similarly treated.

Since our first experiments were carried out somewhat similar results have been obtained by several workers. Hoagland and Mansfield, 5 contrary to their expectations, obtainea entirely negative results in muscle autolyses. Fosse and Rouchelman, 6 employinlg the xanthydrol method, were able to demonstrate a six fold increase of urea in autolyzing liver tissue, a change which mas entirely inhibited by boiling the liver. Fosse 7 believes that the intermediate substance in urea formation is cyanic acid. McCance 8 has endeavored to ascertain the optimum conditions for urea formation in autolyses. He reports urea formation not only in liver but also in spleen.

Data illustrating the results which were obtained in our earlier experiments are given in Table I. As will be noted there is no evidence of any urea formation in the muscle autolyses, but in the liver autolyses colncentration of the urea increased more than ten fold.