Aqueous solutions of dinitrosyl iron complexes with thiol‐containing ligands: isotropic excitable autowave‐generating media

A drop (10 μl) of the glutathione (0.5 mM) – bivalent iron (1 mM) mixture in 15 mM HEPES рН 7.7 applied to the surface of a 0.5 М solution of S‐nitrosoglutathione in the same buffer during the synthesis of a dinitrosyl iron complex (DNIC) with glutathione in a thin (0.3 mm) layer generates autowaves thereby suggesting a space‐time distribution of DNIC in the solution. The autowave pattern changes periodically every 0.4–0.6‐s over a 3‐s period following the addition of the drop to the solution after which the structurized pattern of DNIC dissipates and the solution develops an even green colour as a result of uniform distribution of DNIC. Similar autowaves are recorded in a thin layer of 10 mM DNIC with glutathione after addition of 0.5 М S‐nitrosoglutathione (10 μl) suggesting that solutions of DNIC with thiol‐containing ligands (e.g., glutathione) represent excitable media able to generate autowaves in the non‐equilibrium (excited) state, e.g., in the course of DNIC synthesis by a reaction of S‐nitrosothiols (or NO) with bivalent iron and thiols or after addition of the latter to DNIC in the state of a chemical equilibrium (quiescent state) with its constituent elements. The refractory state required for autowave generation in the given experimental system is characterized by a prolonged induction period characteristic of multistep synthesis of DNIC. Quite probably, the presence of such systems in cells and tissues of living organisms is a necessary prerequisite to effective space‐time control over biological effects of NO and its endogenous derivatives.

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Nitric Oxide ,

Dinitrosyl Iron Complexes ,

Autowaves ,