Amino Acid Correction of Regulatory Volume Decrease Evoked by Hypotonic Stress in Mouse Oocytes In Vitro.

Regulatory volume decrease in response to hypotonic stress is typical of the oocytes and early mouse embryos. Changes in the kinetics of osmotic reaction can be used as a marker of the modulating effect of the incubation medium on transmembrane transport in embryonic cells. Quantitative laser scanning microtomography (QLSM) was used to measure oocyte volume. In this paper, it is shown that addition of 5 µM glycine, taurine, or GABA, as well as ATP to Dulbecco's medium abolished the regulatory volume decrease in mature mouse oocytes.

[Nonspecific effect of Na+/K(+)-ATPase inhibition with strophanthin or under hypothermia in rat heart].

Electron probe microanalysis was applied to study the kinetics of changes in potassium and sodium concentration in muscle cells of isolated heart from Wistar rat during experimental ischemia. Hypoxic perfusion without glucose was shown to evoke the potassium deficiency and sodium accumulation in cardiac myocells. Short-term action (10 min) of strophanthin (0.1 mM/l) recovered Na/K balance in ischemic myocells. Hypothermic perfusion exhibited the opportunity to conserve the cytoplasmic elemental contents in the state corresponding to the beginning of low temperature (4 degrees C) operation.

[Electrone probe microanalysis of rubidium retention in myocell of rat heart during acute ischemia].

In the given investigation contents of potassium and its physiological analog, rubidium, are determined in cardiomyocyte. Applying Electron Probe Microanalysis (EPMA), cytoplasmic concentrations of elements (K, Rb) are measured. The data obtained exhibit that for initial acute ischemia phase the active transport is involved in the uptake of rubidium which competes with potassium entry in cardiac myocell. Then, deep deenergization leads to the intracellular potassium depletion and rubidium retention. This suggests that Rb+ is physiologically not complete analog for K+. Results of combined perfusion with and without rubidium allow us to hypothesize the appearance of cascade of ionic transports to compensate acute ischemic disturbances following the oxygen and substrate deficiency.

[Cyto B dependent and ouabain insensitive regulatory volume decrease in bicellular mouse embryo].

Mouse single-cell embryos exhibit robust Regulatory Volume Decrease (RVD). In what manner the very early mammalian embryo following zygote stage is appreciably altered by the anisotonic extracellular solution is, as yet, totally unclear. Little attention was paid to this direction since there was no way to determine the blastomere volume. This work has served to quantitatively investigate the osmotic response of bicellular mouse embryos employing Laser Scanning Microtomography (LSM) followed with three-dimensional reconstruction (3 DR). We have shown that bicellular mouse embryos in hypotonic Dulbecco's experience RVD. Embryonic cells subjected to hyposmolar exhibit rapid osmotic swelling followed by gradual shrinking back toward their original volume. The van't Hoff law defines swelling phase with the effective hydraulic conductivity of 0.3 micron x min(-1) x atm(-1). Water release during RVD in bicellular mouse embryos is abolished by Cytochalasin B (Cyto B) and the volume recovery is insensitive to ouabain treatment.

[Osmotic behavior of mouse embryonic cells subjected to hypotonic shock].

Osmotic adaptation in a blastomere of mouse embryo has been studied by the direct measurement of the cell volume using laser scanning microscopy microtomography followed by quantitative 3D reconstruction. Embryonic cells subjected to hypotonic shock first swelled and then returned to the initial size. At the beginning of osmotic stress, the swelling occurred by the van't Hoff equation with the water permeability coefficient (L(p)) of 0.4 micro x min(-1) atm(-1). The phase of the regulatory volume decrease was not abolished by Na+/K(+)-ATPase inhibition.

[Analysis of elemental composition (Na/K/Ca) of muscle cells in ischemia in a model of the perfused heart]. / Analiz élementnogo sostava (Na/K/Ca) myshechnoi kletki pri ishemii na modeli perfuzirovannogo serdtsa.

It has been hypothesized that cardiac ischaemia induces some changes in the cardiac myocyte element. In the present study we analysed whether the imbalance of potassium, sodium and calcium in cardiomyocyte may be coupled with ischaemic conditions, using a perfused heard as a model. Electron Probe Microanalysis (EPMA) of papillary muscle cryosection was employed to examine the intracellular content of elements. Following a 30 min acute ischaemia the intracellular potassium was not changed and sodium was reduced. During a prolonged ischaemia (45 min) [K] loss was shown and [Na] concentration was seen reestablished. These results demonstrate that the active transport of potassium and sodium is possible at the beginning of ischaemia. This suggests that under abaerobic conditions Na-K-ATPase may be functionally coupled with an ATP-sensitive K channel through intracellular messenger, possibly ATP.