[Hemoglobin system of golden mullet (Liza aurata, Risso) at adaptation to conditions of outer hypoxia].

Under conditions of experiment, effect of outer hypoxia on the hemoglobin heterogeneous system and respiratory blood characteristics were studied in the golden mullet (Liza aurata R). The control fish groups was maintained at oxygen pressure of 158-162 gPa, the experimental group at 54-55 gPa. Exposure--15 days, water temperature--15 degrees C. Under conditions of oxygen deficit in the mullet body there is noted development of complex of compensatory reactions directed to maintenance of the oxygen blood capacity. Initially (the 1st-2nd day), the release of erythrocytes from spleen is noted, which increases the number of red blood cells and the hemoglobin concentration in blood (emergency adaptation). Then (the 10th-15th day), quantitative readjustments occur at the level of the hemoglobin system, which lead to an increase of blood affinity to oxygen and to a decrease of its sensitivity to pH (long-term adaptation). The revealed changes take place on the background of a decrease of volume of circulating erythrocytes, which reflects the character of change of erythrocytic (MCV, MCHC) and seem to be a consequence of partial dehydration of blood plasma.

[Coupling of membranous and metabolic functions in nucleated erythrocytes of Scorpaena porcus L. in hypoxia (experiments in vivo and in vitro)].

Effect of hypoxia (diapason of 0.57-8.17 mg O2 l(-1)) on functional characteristics of nucleated erythrocytes of the benthonic marine fish Scorpaena porcus L. was studied under conditions in vivo and in vitro. It has been established that characteristic of cellular system of this species is a balanced unhibition of membranous and metabolic functions under conditions of external deficit of oxygen (experiments in vivo). This is expressed in the ability of cells to maintain within norm the intracellular ATP concentration and transmembrane gradients for Na+ and K+ with low activities of Na+, K(+)-ATPase and hexokinase. This phenomenon seems to be based on the process of a decrease of the number of functioning ion channel at the level of the cell cytoplasmic membrane; this process reduces energy expenditure for maintenance of cationic gradients (the phenomenon of metabolic arrest). The same is also indicated by an increase of intensity of fluorescence of FDA and R123 in the scorpaena erythrocytic suspensions in hypoxia (experiments in vitro). Mechanisms underlying this phenomenon are discussed.

[Stoichiometry of cytochromes and oxygen tension in skeletal muscles of marine fish].

The character of oxygen tension distribution and peculiarities of cytochromes stoichiometry in skeletal muscles of bottom and pelagic species of marine fish were compared. It is shown, that the limitation of muscle activity increases the number of hypoxic zones in the muscle tissue. The mitochondrial electron-transporting chain then obtain the uncompensated type of organization, expressed in the increase of the share of the terminal complex aa3 on the background of general reduction of cytochromes content in the muscles. The reaction is of an adaptive character and can be implemented by pelagic fish species in conditions of experimental hypokinesia.

[Oxygen binding by marine fish blood under hypothermic experimental conditions].

Influence of temperature in the range of 1-15 degrees C on oxygen binding properties of blood of thermophilic--golden mullet (Liza aurata), anchovy (Engraulis encrasicolus), and cold-tolerant--sardelle (Clupeonella cultriventris) fishes has been investigated under experimental conditions. Heat dependence of oxygenation reaction in thermophilic fish blood at temperature below 10 degrees C considerably increases, which is evidenced by high deltaH values. That is accompanied by a substantial increase of blood oxygen affinity and complicates blood deoxygenation at the tissue level. This reaction is apparently determined by the change of hemoglobin interaction with intraerythrocyte medium. The concentration of NTP in erythrocytes increases, that partially compensates negative changes of blood oxygen affinity (parameter P50 is raised) under long-term maintenance of fishes at 5 degrees C. However this reaction is not observed at low temperatures (1-2 degrees C).

[Contents of monovalent cations and ATP in erythrocytes of marine fishes in experimental hypoxia].

Coupling of membrane and metabolic functions in nuclear erythrocytes was investigated under experimental hypoxia conditions in fishes (Liza aurata, Scorpaena porcus) with different tolerance to oxygen deficiency. It was shown, that resistant to hypoxia Scorpaena porcus keeps in erythrocytes transmembrane gradients of K+ and Na+ and cellular concentration ATP under 15% of oxygen saturation of sea water. It was connected with the decrease in Na+, K+ -ATPase and hexokinase activity. The reaction to oxygen deficiency was opposite in sensitive to hypoxia Liza aurata erythrocytes. A decrease in ionic gradients and concentration of ATP in red blood cells was observed while the activity of Na+, K+ -ATPase and hexokinase was high. The reasons of the differences obtained are discussed.

[Haemoglobin system of Black Sea round goby under experimental hypoxia conditions]. / Gemoglobinovaia sistema chernomorskogo bychka-krugliaka v usloviiakh éksperimental'noi gipoksii.

Haemoglobin of the Black Sea round goby (Neogobius melanostomus P.) resisting to external hypoxia was studied. Haemoglobin of this species was fractionated into 4 components (2 minor and 2 major ones) by the disk-electrophoresis in polyacrylamid gel. The major fractions were eluted and their respiration parameters were investigated. One of them showed high affinity for O2 (P50 5.81 +/- 0.74 mm Hg at pH 8.3) and heightened sensibility to pH (Bohr effect amounted to -0.81 +/- 0.09 at pH of 8.3 --> 7.5) simultaneously. Moreover, an acidosis incubation medium (pH 8.3 --> 7.5) decreased its O2 saturation by 12.8 +/- 1.4% (Root effect). The level of this fraction increased by 41.8% (p < 0.001) under the experimental hypoxia conditions (seawater O2 concentration range was 1.7-1.8 mg 1(-1); exposition--10 days). It affected blood respiration parameters and reflected the process of adaptation of this species to oxygen deficiency. The nucleotidtriphosphate level in red blood cells did not change. Swelling of circulated erythrocytes was observed simultaneously.