DETERMINATION OF POLY(ADP-RIBOSE) POLYMERASE IN RAT-BLOOD LYMPHOCYTES- POSSIBLE RELEVANCE TO GENOTOXIC EXPOSURE OF HUMANS

In this report is described a method for the measurement of the endoge nous poly(ADP-ribose) polymerase (pADPRP) activity in permeabilized ly mphocytes isolated from peripheral blood samples. The potential use of the data obtained by this technique is proposed for biomonitoring hum an exposure to genotoxic agents. This multifunctional nuclear catalyti c protein is involved in basic cell functions, but a major role is ass ociated with DNA synthesis and DNA repair activity. In fact, this enzy me is promptly stimulated by DNA strand breaks or by free ends induced by endogenous or exogenous agents. This rapid increase of the basal a ctivity level can be used to reveal biological modifications early aft er exposure to physical or chemical agents. During isolation and perme abilization of blood lymphocytes, DNA structure remained unaltered. Th erefore, no artificial activation of the endogenous pADPRP activity wa s observed. This technique combines the radiometric assay of pADPRP wi th the isopycnic isolation of blood lymphocytes; results are reliable, reproducible, and easily applicable to small blood specimens from tre ated animals or humans. The data presented in this report add confiden ce to the correlation between endogenous pADPRP level and DNA damage e xtent in hepatocytes and peripheral blood lymphocytes after in vivo ex posure. Preliminary data on lymphocytes from humans are also reported.