Iu. V. Danylovych, S. A. Karakhim
In the presence of vesicular preparations of sarcolemma (near 70% reverse cytoplasmic sideways inward) fluorescence of ANS – 1-(fenilamino)-8-naftylamine – rises more than 10 times. In the conditions of increase of concentration of sodium nitrite and hydrogen peroxide from 1 to 5?µM the probe fluorescence diminishes. Extinguishing of ANS fluorescence under the action of nitrite anions can be explained by chemical modification of the positively charged superficial groups (amino- and sulfhydrile). It will result in the decrease of amounts of local “+”-charges on a membrane, proper decrease of fastening ANS with a membrane and fluorescence extinguishing. Н2О2 is able to oxidize superficial –SH-groups which carry a partial positive charge. Consequently a decrease of general amount of fixed “+” charges on a membrane, diminishing of ANS fastening with sarcolemma and the proper fluorescence extinguishing takes place. Probed and calculated by the method «ion beats» superficial closeness of charges of vesicular preparations makes 2.3?±?0.1 mC/m2. At the action of 50 µM sodium nitrite and hydrogen peroxide it diminishes to 2.0?± 0.1 mC/m2 and 1.7?±?0.07?mC/m2 accordingly. The less effective action of NaNO2 can be determined by the influence of Na+ on the superficial field of membrane. With the purpose to confirm the previous suppositions we used the method of laser-correlation spectroscopy, that registered the mean value of hydrodynamic diameter (GD) of vesicules and their division by sizes. Middle GD makes in control 327 ± 16 nm, and GD which is most often met in population – 291 ± 11 nm. Adding of nitrite anions to the system in a growing concentration results in the substantial decline of GD of both all the membrane population and of plasma vesicules. Analogous results are obtained in the case of Н2О2. In the presence of specific modifiers of sulfhydrile- and aminogroup of membrane surface (DTT and TNBS) the decline of GD under the action of nitrite anions or hydrogen peroxide is not observed, or diminishes substantially. Consequently, the diminishing of GD in our system under the action of the probed compounds can be related to chemical modification of amino or/and sulfhydrile groups of membrane surface which complements and confirms experiments with ANS. Diminishing of density of superficial positive charges is possible under the condition of the action of nitrogen oxides and hydrogen peroxide on the membrane can result in strengthening of cations interaction with a membrane and, in principle, will influence their reception and transport.
Key words: superficial potential of membrane, ANS, nitrogen oxide, hydrogen peroxide, method of laser-correlation spectroscopy, myometrium.
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