[Formation of dinitrosyl iron complexes in cardiac mitochondria]

It has been established that, in the presence of S-nitrosothiols, cysteine, and mitochondria, dinitrosyl iron complexes (DNIC) coupled to low-molecular-weight ligands and proteins are formed. The concentration of DNIC depended on oxygen partial pressure. It was shown that, under the conditions of hypoxia, the kinetics of the formation of low-molecular DNIC was diphasic. After the replacement of anaerobic conditions of incubation to aerobic ones, the level of DNIC came down; in this case, protein dinitrosyl complexes became more stable. We proposed that iron- and sulfur-containing proteins and low-molecular-weight iron complexes are the sources of iron for DNIC formation in mitochondrial suspensions. It was shown that a combination of DNIC and S-nitrosothiols inhibited effectively the respiration of cardiomyocytes.