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FIGURE 3
Formation of methemoglobin inside of erythrocytes under action of SNICs.
The releasing of NO from SNIC may be represents by following scheme:
k
1
→
(4)
[
Fe
(
SR
)(
NO
)]
4
NO
+
[
decomposition products
]
2
2
4
NO penetrating into erythrocytes reacts with oxyhemoglobin [9]:
k
2
→
2
+
3
+
−
NO
+
HbFe
"
O
HbFe
+
NO
(5)
2
3
Obtained kinetic dependence (Figure 3) and determined the effective first order rate
constants characterize the rate of reaction (5) in presence of studied SNICs. Same as
the rate constants characterize NO-donating ability of SNICs. In accordance with this
NO-donating ability of Cys must be about 10 times lower than one of Pym. Compar-
ing the hemolytic activities given complexes (induction periods, Figure 2) we see that
they dependent from their NO-donating abilities. Namely, the slighter donor, Cys have
larger induction period of hemolysis in comparison with Pym. Thus, obtained result
allows interpreting presence certain interrelation between the level of NO formation
and subsequent hemolysis of erythrocytes.
Earlier results evidence that the main origin of cytotoxicity is not NO itself, but the
product of bimolecular interaction NO and superoxide anion radical is peroxynitrite
[10]:
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