ENHANCED SENSITIVITY TO THE LETHAL AND MUTAGENIC EFFECTS OF PHOTOSENSITIZING ACTION OF CHLORPROMAZINE IN ETHYLENEDIAMINETETRAACETATE-TREATED ESCHERICHIA COLI

Abstract— Ethylenediaminetetraacetate (EDTA) treatment of Escherichia coli H/r30 (Arg_-) enhanced cell sensitivity to the lethal and mutagenic effects of the photosensitizing action of chlorpromazine (CPZ). The most obvious effect of EDTA on the fluence-survival curve was an elimination of the shoulder. In the absence of EDTA, CPZ plus near-UV radiation did not induce the reversion from arginine-auxo-troph to autotroph of E. coli H/r30. However, when EDTA (5 mM)-treated cells were subjected to CPZ plus near-UV radiation, the induced reversion frequency increased with time of irradiation. It is concluded that the enhanced penetration of CPZ into E. coli cells by EDTA facilitates the drug binding to DNA within the cells upon near-UV irradiation and that this is the cause for the enhanced photosensitized lethal and mutagenic effects of CPZ.