Induction of micronuclei in V79 cells after combined treatments with heterocyclic aromatic amines.

Heterocyclic aromatic amines (HAs) appear in foods rich in proteins when subjected to different cooking processes. These amines have been demonstrated to be mutagenic in bacteria; in eucaryotic cells, controversial results have been referred. The objective of this study is to evaluate the clastogenic and/or aneugenic capacity of three HAs--2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx), and 2-amino-3-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)--in isolated as well as in combined treatments. The micronucleus test in vitro was used on V79 cells in the presence and absence of metabolic activation. The duration of the treatment was 2 h, and cytochalasin B was added for 21 h to stop cytokinesis; then, micronuclei (MN) were counted in binucleated cells. In the presence of metabolic activation, the three amines showed a significant increase in the number of MN with respect to the negative control. The PhIP amine presented the highest values and it also resulted slightly active in the absence of metabolic activation, although these differences have not been considered to be significant. The combined treatments of these amines have shown that the effects attributed to them when administered together are those that are expected for a possible additive effect; the effect attributed to each HA separately is not potentiated nor inhibited.