Membrane-bound ferriform hemoglobin in nuclear erythrocytes of the sea ruff (<i>Scorpaena porcus</i>, Linnaeus, 1758)

The content of the membrane-bound methemoglobin fraction (MtHb) in the nuclear erythrocytes of the sea ruff (Scorpaena porcus, Linnaeus, 1758) was studied in vitro. The spectral characteristics of whole hemolysate, hemolysate after stroma deposition (purified hemolysate), and resuspended stroma were studied. It was found that the proportion of MtHb in the stroma of erythrocytes exceeded 80% (6.20 ± 0.59 µM). The purified hemolysates practically did not contain MtHb (0.5 ± 0.2 µM). The presence of a membrane-bound ferriform did not affect the resistance of erythrocytes to osmotic shock. The osmotic resistance limits determined using the LaSca-TM microparticle laser analyzer (BioMedSystems, Russia) (102–136 mOsm kg–1) coincided with those noted for other bony fish species. The nitrite load (10 mg l–1) caused a significant increase in the MtHb content in the blood. However, the level of the membrane-bound ferriform did not change significantly and amounted to 6.34 ± 1.09 µM (about 95%). This indicates the functional expediency of its presence in this structure. The presence of MtHb in the cytoplasmic membrane of nuclear erythrocytes, apparently, allows cells to neutralize the external oxidative load and the toxic effect of hydrogen sulfide in the bottom layers of water in which the sea ruff lives.