Ecto-ATPases, morphometry and heat production activity of erythrocytes of cartilaginous and teleost fishes of the Black Sea

The activity of ecto-ATPase and the size characteristics of erythrocytes in two species of cartilaginous and ten species of bony fishes, as well as the heat-production activity of the erythrocyte suspension in Scorpaena porcus and Raja clavata were studied. It was shown that the activity of ecto-ATPase of red blood cells (RBC) between cartilaginous fishes differs by 1.5 times and is 3.1 nmol Fn/min/μl RBC in Raja clavata, and 2.1 nmol Fn/min/μl RBC in Dasyatis pastinaca. Erythrocytes of teleost fish are characterized by a more significant variability of ecto-ATPase activity, which differed between its extreme values by more than 60 times (in Scorpaena porcus it was 6.4 nmol Fn/min/μl RBC, in Spicara flexuosa and some other species – 0.1 nmol Fn/min/μl RBC). When comparing the size characteristics of erythrocytes and the values of ecto-ATPase activity, a direct relationship was shown between these indicators. A study of heat production in suspensions of thresher and scorpionfish erythrocytes showed that adding ATP to a suspension of isolated cells (1 mg/ml) significantly increased the temperature in the experimental cell. The erythrocytes of the thresher and scorpionfish demonstrated different heat generation dynamics. Thus, ΔT generated by stingray erythrocytes was almost two times lower than in scorpionfish erythrocytes. The total duration of the heat generation process to the maximum ΔT in the thresher erythrocyte suspension was almost four times shorter than in the thresher. However, the process of temperature reduction in the thresher erythrocyte suspension occurred more than two times slower than in the thresher. The results obtained showed that ecto-ATPases of fish erythrocytes apparently function as a source of local heat generation on the erythrocyte surface and, thus, can be deeply integrated into the functioning of the cell membrane and the entire blood flow as a whole.