[Neutral DNAse activity in rat tissues in radiation carcinogenesis]. / Aktivnost' neitral'noi DNKazy v tkaniakh krys pri luchevom kantserogeneze.

The activity of neutral DNAse and its natural protein inhibitor was determined in the liver, brain and spleen of albino rats with malignant tumours of mammary gland and other organs. The tumours appeared 14-20 months after the irradiation of rats with fast neutrons (0.5-1.0 Gy). It is shown that the activity of DNAse I and its protein inhibitor increases in the liver and brain of tumour-bearing rats, while the enzyme and inhibitor capacity to form the nuclease-inhibitor complex decreases, especially in the liver. It is suggested that the increase in the DNAse activity in the tumour-bearing rats liver is important in the antitumour activity of the organism.

[Activity of DNAase I inhibitor in subcellular fractions of rat tissues]. / Aktyvnist' inhibitors DNK-azy I u subklitynnykh fraktsiiakh tkanyn shchuriv

The inhibitory activity in the mitochondrial and postmitochondrial fractions of the liver, spleen and thymus of albino rats was studied with respect to pancreatic DNase I. It is shown to be due to the presence of thermolabile substances of protein nature (natural inhibitors of DNase I) in the subcellular fractions of the organs under study. A higher inhibitory activity is detected in the postmitochondrial fraction of all the tissues under investigation. The lowest inhibitory activity is found in the mitochondrial and postmitochondrial fractions of the liver. The data of a simultaneous study of changes in the activity of tissue DNase and inhibitory activity in the subcellular fractions give reasons to suppose the presence of the nuclease-inhibitory complex in the tissues.