The effect of Mg2+ on the mitochondria toxication induced by adriamycin (ADM)

The 3p-NMR Spectra and the fluorescence intensity of labeling NBD-PE of mitochondrial FF0-ATPase showed that ADM induced the lipid phase transition of mitochondrial membrane but Mg2+ inhibited this effect. Besides, ADM could induce the decreasing of membrane lipid fluidity, increasing the membrane lipid molecule packing by using fluorescent probe DPH and MC 540 and Mg2. exerted the protective effects as well. By investigating the conformational change of the membrane protein FF0-ATPase the intrinsic tryptophan fluorescence was measured. It indicated that the fluorescence was decreased by ADM but Mg2+ inhibited the decreasing. For mechanism study, it was found that Mg 2 could significantly inhibit ADM to bind to SMP by about 30%. In the presence of NADH and mitochondria or SMP the free radical signal of ADM semiquinone was monitored by ESR technique. The signal appeared and reached maximum in a few minutes. Mg2 could decrease the intensity of sinal which was dependent on the Mg-'+ concentration. It is also evidenced by that Mg + could protect mitochondrial membrane from lipid peroxidation induced by ADM. And the Symmetric Spectrum of ADM semiquinone free radical changed into a completely immobilized spectrum and Mg2+ could delay this process. These results mentioned above could be concluded as follows: Both ADM and Mg2 competitively interact with mitochondrial inner membrane, In the case of ADM it could induce the lipid polymorphism on one hand and produce semiquinone free radical on the other hand, thus influencing the conformation and function of the membrance protein embedded in the membrance lipids and producing lipid peroxidation which could exert toxic effect on membrane. Mg2. could antagonize the ADM induced effect by reacting with membrane in place of ADM.