The Effect of Azide, Fluoride, Orthovanadate and EDTA Sodium Salts on Ecto-ATPase Activity in Erythrocytes of a Scorpionfish (Scorpaena porcus L.) and Thornback Ray (Raja clavata L.).

Silkin, Yu. A.; Silkina, E. N.; Silkin, M. Yu.

The effect of azide, fluoride, orthovanadate and EDTA sodium salts on the ecto-ATPase activity in erythrocytes of a scorpionfish (Scorpaena porcus L.) and thornback ray (Raja clavata L.) was studied. It was shown that under the influence of millimolar (mM) concentrations of the selected biochemical agents, significant differences in the hydrolytic activity of erythrocyte plasma membrane ecto-ATPases were revealed in cartilaginous vs. teleost fish. For example, thronback ray erythrocyte ecto-ATPase was practically insensitive to sodium azide. In contrast, scorpionfish erythrocyte ecto-ATPase was sensitive to sodium azide, which blocked the enzyme activity by 65% at a concentration of 20 mM. Thornback ray erythrocyte ecto-ATPase retained a significant activity (37%) at high (60 mM) concentrations of sodium fluoride, while scorpionfish erythrocyte ecto-ATPase was almost completely blocked at this concentration. EDTA acted as a modifier of thornback ray ecto-ATPase activity: at concentrations of up to 6 mM, ATP hydrolysis was actively blocked (by 58%), and at higher concentrations, ecto-ATPase activity was stimulated (up to 20%). An increase in the EDTA concentration (up to 12 mM) in suspensions of scorpionfish erythrocytes constantly stimulated the inhibitory effect of the chelator (up to 52% vs. control). The activity of ecto-ATPases in erythrocyts of the studied fish species was weakly blocked by sodium orthovanadate. These differences may reflect a higher tolerance of thornback ray erythrocyte ecto-ATPase to the effect of the above chemical reagents compared to a scorpionfish. The absence of the sodium azide inhibitory effect on thornback ray erythrocyte ecto-ATPase suggests that this ecto-ATPase may be referred to a family of type 2 ecto-NTPDases (ENTPD2), while scorpionfish ecto-ATPase may belong to type 1 ecto-NTPDases (ENTPD1).

SODIUM salts; ERYTHROCYTES; ERYTHROCYTE membranes; CELL membranes; SODIUM azide; ETHYLENEDIAMINETETRAACETIC acid; SODIUM fluoride

Journal of Evolutionary Biochemistry & Physiology, 2021, Vol 57, Issue 5, p1008

0022-0930

Academic Journal

10.1134/S0022093021050033