The effect of Ehrlich ascites tumour growth on lactate dehydrogenase activities in tissues and physiological fluids of tumour bearing mice

Abstract

1. 1. Tumour growth kinetics and the activity of lactate dehydrogenase (LDH) in body fluids and host tissues were studied during the Ehrlich ascites tumour growth. The rate of tumour cell death was determined by measuring the loss of 125I from mice bearing [5- 125I]iodo-2′-deoxyuridine labelled tumour cells. 2. 2. The activity of LDH in serum increased progressively with increasing tumour mass during the first period of tumour growth, whereas that of cell free ascites fluid exhibited a peak level during early plateau phase growth. The analysis of LDH activity in cell free ascites fluid revealed that the increased LDH activity could only partly be attributed to a release from dead tumour cells. 3. 3. A marked increase in host liver LDH activity was observed. In addition, the growing tumour induced an increase in RNA synthesis activity and Kupffer cell proliferation in the liver. The LDH activity in skeletal muscle decreased significantly with increasing tumour mass. 4. 4. The observations show that the growing tumour exerts a marked effect on the metabolic activity of host tissues. It is suggested that an altered metabolism affects the cell membrane integrity of certain host tissues and causes a leakage of LDH molecules, which contributes to the increased extracellular LDH activity of tumour bearing animals.