The Resistance of Erythrocytes in Some Black Sea Hyposmic Fishes Exposed to the Nonionic Detergents Triton X-100 and Tween-20

—The osmotic resistance of erythrocytes and the hemolytic effect of nonionic detergents, Triton X‑100 and Tween-20, on red blood cells were analyzed in four hyposmiс Black Sea fish species: horse mackerel ( Trachurus mediterraneus ponticus Aleev), gilthead ( Diplodus annularis L.), black scorpionfish ( Scorpaena porcus L.) and thornback ray ( Raja clavata L.). It was revealed that in physiological solutions, red blood cells from hyposmic thornback ray and black scorpionfish were highly resistant to a hypotonic environment. By determination of the concentration of physiological solution in which 50% of fish erythrocytes ( C 50% ) were hemolyzed during incubation it was possible to rank fish erythrocytes according to the degree of osmotic resistance in the following order: black scorpionfish > thornback ray > gilthead > horse mackerel. The erythrocytes of the investigated teleost fishes exhibited a clear dependence on the mobility by C 50% , which increased in some fish with a decrease in their motor activity. Triton X-100 did not induce an increase in resistance or even weakly stimulated an increase in the hemolytic activity of erythrocytes in gilthead and thornback ray. In the presence of Triton X-100 in horse mackerel erythrocytes, cell resistance increased by a factor of 4.7 in an incubation medium with 50% dilution. Protective properties of Triton X-100 were seen during incubation of black scorpionfish erythrocytes in media with 70% dilution. Tween-20 also increased the resistance of fish erythrocytes to hemolysis. The results of this study demonstrated that Tween-20 and, in some cases, Triton X-100, are useful in maintaining stability of fish erythrocyte suspensions during experimental studies.