G. V. Danylovych, Yu. V. Danylovych
The action of sodium nitroprusside, nitrite-anions and hydrogen peroxide on Са2+,Mg2+-АТРаse and Mg2+-АТРаse (Са2+-independent) enzymatic activity in myometrium sarcolemma fraction is investigated. It is established, that 0.1?mM sodium nitroprusside and 10-8–10-5 M nitrite-anions essentially reduce Са2+,Mg2+-АТРаse activity whereas Mg2+-АТРаse proved to be absolutely resistant to them. At rather high concentration of nitrite-anions (0.1 mM) appreciable stimulation of Са2+,Mg2+-АТРаse was observed. Hydrogen peroxide (10-8–10-4), depending on the concentration suppressed both enzymes activity. However, Са2+,Mg2+-АТРаse proved to be more sensitive to the action of H2O2 (seeming Кі = 0.42 ± 0.1 µM), than Mg2+-АТРаse (seeming Кі = 3.1 ± 0.9 µM). At presence of 1 mM ditiothreitole (a reducer of SH groups of the membrane surface) action of investigated substances considerably decreased. Reagents on carboxic- (dicyclogexilcarbodiimid) and amino- groups of the membrane (trinitrobenzolsulfonic acid) inhibited both Са2+,Mg2+-АТРаse, and Mg2+-АТРаse activity in membrane fractions. In the presence of noted reagents sodium nitroprusside and nitrite-anions action was not almost shown. Hence, nitrogen oxide, nitrite-anions and hydrogen peroxide suppress Са2+, Mg2+-АТРаse and Mg2+-АТРаse (only hydrogen peroxide) activity in the plasmatic membrane of myometrium cells, and this action can be connected with direct updating of superficial chemical groups of the membrane.
Key words: Са2+,Mg2+-АТРаse, Са2+-independent Mg2+-АТРаse, nitric oxide, hydrogen peroxide, myometrium.
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