Protective effect of magnesium on DNA strand breaks induced by nickel or cadmium.

Magnesium, an essential metal that is important in the normal functioning of DNA, has been shown to interact with some of the toxic heavy metals in respect to biochemical and molecular mechanisms and in altering the tumorigenic process. This study examined the influence of magnesium in combination with nickel and cadmium in respect to damage of the DNA molecule. The purpose of this study was to evaluate the influence of magnesium on the amelioration of the toxic metals nickel and cadmium in respect to sustaining DNA damage. Two types of lymphocytes were used, i.e., primary Fischer 344 rat splenocytes and AHH-1 TK+/-, a human B-lymphoblastoid cell line that has been spontaneously transformed. These cells were grown in either a magnesium-free or magnesium-supplemented RPMI 1640 medium that was specifically formulated for this study. A 2 x 2 factorial design was employed with magnesium and either nickel or cadmium serving as the two factors. The experimental groups were as follows: +Mg+Ni, +Mg-Ni, -Mg+Ni, -Mg-Ni, with cadmium alternating for the nickel in the subsequent studies. The nickel or cadmium was added at a concentration of 50 mumol/L. The presence of double-stranded DNA was determined in each of the respective treatment groups with the two types of cell lines. Based on the results of this study, nickel is not directly toxic to DNA, whereas cadmium produces damage directly on the DNA molecule.(ABSTRACT TRUNCATED AT 250 WORDS)