CHANGES IN METABOLISM OF INORGANIC POLYPHOSPHATE IN RAT-TISSUES AND HUMAN-CELLS DURING DEVELOPMENT AND APOPTOSIS

Age-dependent studies show that the amount of inorganic polyphosphate in rat brain strongly increases after birth. Maximal levels were found in 12-months old animals. Thereafter, the concentration of total poly phosphate decreases to about 50%. This decrease in the concentration o f total polyphosphate is due to a decrease in the amount of insoluble, long-chain polyphosphates. The amount of soluble, long-chain polyphos phates does not change significantly in the course of ageing. In rat e mbryos and newborns, mainly soluble polyphosphates could be detected. In rat liver, the age-dependent changes are less pronounced. The chang es in polyphosphate level are accompanied by changes in exopolyphospha tase activity, which degrades the polymers to orthophosphate; highest enzyme activities were found when the polyphosphate level was low, Ind uction of apoptosis in the human leukemic cell line HL-60 by actinomyc in D results in degradation of long polyphosphate chains. The total po lyphosphate content does not change significantly in apoptotic cells.