Urinary Excretion of Acid and Neutral Deoxyribonuclease by Rats under Normal and Post-Irradiation Conditions

Abstract

INTEREST in devising methods of studying tissue breakdown after irradiation has led us to investigate the deoxyribonucleases in body fluids on the premise that these enzymes are liberated only by damaged or destroyed cells. We have reported previously on the increased urinary excretion of the neutral deoxyribonuclease by rats exposed to lethal doses of X-rays¹. The purpose of the present communication is to describe a similar but more prompt increase in the urinary excretion of an acid deoxyribonuclease (pH optimum 5.6) by irradiated rats. This is the enzyme which has been studied recently in extenso by Allfrey and Mirsky². It has been found in many tissues, especially those capable of active proliferation. The urinary acid deoxyribonuclease is partially inhibited by magnesium ion and citrate (0.1 M); its activity is not affected by antimony sulphate, sodium arsenate and extract of the pigeon crop gland, all of which inhibit the neutral deoxyribonuclease^3,4.