In this investigation of the significance of elevated levels of serum aldolase in rats bearing the Walker carcinosarcoma 256 it was found that the enzyme content in the blood leaving the tumor was higher than in heart blood. Surgical removal of the tumor caused the level of serum aldolase to fall promptly to the normal range, the rate of fall paralleling the rate of disappearance of crystalline aldolase injected intravenously. Anemia, cachexia, and the presence of the spleen or the adrenal glands were unrelated to the level of the serum enzyme. X-ray treatment of the tumor, or the administration of urethan, aminopterin, or nitrogen mustard, usually caused a fall in the elevated level of the enzyme.

In experiments with tissue slices, aldolase was released from tumor tissue into the medium under anaerobic conditions, particularly when glucose was not added to the medium. In the presence of oxygen and glucose, aldolase was retained in the cells.

Bilateral nephrectomy or bilateral ligation of the ureters caused an increase of serum aldolase in normal rats; these procedure delayed but did not prevent the disappearance of intravenously injected crystalline aldolase. Ligation of the bile duct did not produce an increased amount of aldolase in the blood serum.

The evidence provided by the data assembled indicates that the elevated levels of serum aldolase result from its increased liberation from the tumor, at a rate exceeding its elimination from the circulation. It is suggested that this increased liberation derives from foci of necrosis in the tumor and that it is not a characteristic of malignant tissue per se.


Abridgment of thesis submitted by Dr. Sibley to the Faculty of the Graduate School of the University of Minnesota in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Urology.

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