[Ca2+ transport in the sarcolemma of the myometrium under its chemical modification]

The effect of some chemical modifying agents of the sarcolemma surface--dicyclohexicarbodiimide, trinitrobenzolsulphuric acid, dithiotreitol and nitrit-anions on passive transsarcolemmic accumulation of Ca2+ by the pig myometrium sarcolemma property oriented vesicules was studied. The comparative analysis of these substances action under proton transmembrane gradient dispersion is presented. The significance of surface amino-, carboxy groups and disulphide membrane bounds in Ca2+ transport mechanisms as a corresponding aspect to some contemporary ideas about Ca(2+)-channel has been defined. The hypothesis is made that the proton transmembrane gradient dissipation leads to dislocation of carboxyl groups and disulphid bounds in relation to the membrane surface resulting in increasing Ca(2+)-permeability of the sarcolemma. The increase of sarcolemma permeability for Ca2+ under the action of 10 nM NO-2 was demonstrated. On the base of experimental data the supposition was made that NO-2 modified amino- and carboxylate groups of the sarcolemma surface. Under the chemical modification of these groups the nitrit-anions inhibit transsarcolemmic Ca2+ movement. NO-2 is not a result of sarcolemma surface SH-groups oxidation, while possibly NO2- protects some functionally important disulphide bridges of Ca(2+)-channel from their chemical restoration.