[Role of extra- and intracellular Ca2+ in changes of NO2- and H2O2 production by endometrium].

The work is aimed to find out the role of extra- and intracellular Ca2+ in cyclic mechanisms of NO2- and H2O2 metabolism in the stroma cells of endometrium activated by acetylcholine. High activity of Mg2+, Ca(2+)-ATP-ase is characteristic of stroma cells of the endometrium. This activity is tested in the presence of 0.01% of the Triton X-100 (36 +/- +/- 2 mumole Pi/mg of protein for 1 hour). The acetylcholinesterase activity in these systems is equal to 9.8 +/- 0.2 mumole thiocholinebromide/mg of protein for 1 hour. Acetylcholine (10 microM) elevated essentially the concentration of cytosolic Ca2+ in them. It was established, that in the control the suspension of stroma cells produced 1 nmol/NO2-/10(6) of cells, this value being constant for the experimental period of time in the range of 5-60 s. The activation of cells (1 microM acetylcholine + 10 microM Ca2+) results in the appearance of cyclicity (maxima on 5, 15 and 60 s) and 5-fold intensification of NO2- production. The rise of extracellular concentration of Ca2+ up to 0.1-1--10 mM results in essential change of the character of the time dependence of NO2- metabolism and only in inappreciable intensification of the response amplitude. Such a pattern is observed for H2O2: 0.77 mumol H2O2/10(6) of cells in the control, at 10 microM Ca2+ maxima of production on the 5 and 30 s, change of the form of the time response, instead of the amplitude under the increase of concentration of extracellular Ca2+. Preincubation of cells with modifiers endoplasmic reticulum ryanodine, caffeine (1 mM) and heparine (10 mM) results in essential drop of NO2- production and infringement of cyclicity, the effect of ryanodine being more expressed on 5 s, than on 15 s, and heparine--also on 5 s, and on 15 s. Preincubation of cells with methylene blue (10 mM), which inhibits guanilate cyclase, result in considerable intensification of NO2- and H2O2 formation and cyclicity losses. Dynamics of NO2- formation (is controversy) reciprocated with cGMP, whereas nitrosoglutathione production and NO3- tends to saturation in the course of time. Thus, acetylcholine-dependent variations of NO2- and H2O2 concentrations in the suspension of stroma cells depend on the state of extra- and intracellular Ca(2+)-stores, are controlled by cGMP. It may be assumed, that the NO2- production minima are caused by its transfer in NO3- and its binding with glutathione.