[Specificity of tetrodotoxin effect in mollusc neurons].
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Biomedical subjects
N K Chemeris
Publications and source records attributed to N K Chemeris.
[A weak low-frequency magnetic field initiates the frequency dependent fluctuations of Daphnia magna heart contraction period].
The influence of low-frequency (16 Hz) sinusoidal magnetic field on period of Daphnia magna heart beatings was studied. Heart beatings were registered by optical method. Fluctuations of period of heart beatings were analyzed using fast Fourier transform algorithm. It was shown that alternating (16 Hz) magnetic field with magnetic induction of 140 microT combined with direct magnetic field (magnetic induction of 21 microT) causes the appearance of frequency-dependent maxima in the power spectra of heart beating fluctuations. The dynamics of the field effect was studied as the phases of its development, rise and fall, as well as temporal characteristics were determined. It was proposed that sensor of low-frequency magnetic field is incorporated in one of the regulatory pathways, controlling rhythmical beating activity.
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[Modification of the activity of murine peritoneal neutrophils upon exposure to millimeter waves at close and far distances from the emitter].
The comparison of horn, dielectric and channel antennae on their matching with various types of loads, including a biological object, is carried out. The channel antenna in contrast to dielectric and horn ones provides the uniform spatial distribution of specific absorbed rating in the frequency range used and wide-band matching with the object both in near field and far field zones of the radiator. It is shown, that low-intensity electromagnetic radiation of extremely high frequency in near field zone of the channel radiator modifies the activity of mouse peritoneal neutrophils on a quasi-resonance manner. The interaction of electromagnetic radiation with the biological object has been revealed in the narrow-band frequencies of 41.8-42.05 GHz and consists in inhibition of luminol-dependent chemiluminescence of neutrophils activated by opsonized zymosan. It is not found any frequency dependence of the electromagnetic radiation effects in the far field zone of the radiator. The results obtained suggest, that the quasi-resonance dependence of the biological effect on the frequency of the electromagnetic radiation in the near field zone is conditioned by structure and nature of the electromagnetic radiation in this zone.
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[Single Ca2+-activated K+-channels in cultured kidney cells Vero].
Using the patch voltage-clamp method ("inside-out" mode) properties of single Ca(2+)-activated K+ channels in cultured kidney cell Vero were studied. Two types of kinetically distinct channels (fast and slow) were found. The fast and slow channels differ by single channel conductance, kinetic parameters, characteristics of interaction with Ca2+, and voltage dependency degree of the kinetics parameters, but are similar in ionic selectivity in respect to monovalent cations. It was found that the channel conductance varies from patch to patch between 140 and 230 pS. Average values of single channel open duration and an apparent dissociation constant were correlated with the single channel conductance. The relationship was found: the more the conductance the lesser the open time duration and more the dissociation constant. The data suggest that there is almost continuous spectrum of subtypes of the Ca(2+)-activated K+ channels, the fast and slow channels being extreme groups of this spectrum. The data are regarded from the viewpoint of the clustery hypothesis.
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[Modulated extremely high frequency electromagnetic radiation of low intensity activates or inhibits respiratory burst in neutrophils depending on modulation frequency].
The influence of low-intensity modulated electromagnetic radiation of extremely high frequencies (EHF EMR) on synergistic reaction of calcium ionophore A23187 and phorbol ester PMA in activation of the respiratory burst of the peritoneal neutrophils of mice line NMRI was investigated. The production of reactive oxygen species by the neutrophils was estimated by luminol-dependent chemiluminescence technique. The cells were irradiated in the far field zone of the channel radiator for 20 min in the presence of A23187 and then were activated by PMA after switching off the irradiation. It was shown, that continuous EHF EMR (50 microW/cm2) inhibited quasi-resonantly the synergistic reaction. The maximum effect was about 25% at carrier frequency of 41.95 GHz. Modulated radiation with carrier frequency of 41.95 GHz and modulation frequency of 1 Hz activated the synergistic reaction, but at modulation frequencies of 0.1, 16 and 50 Hz inhibited one. At fixed modulation frequency of 1 Hz the nonlinear dependence of the effect on the carrier frequency was found. The synergistic reaction was activated in the frequency range of 41.95-42.05 GHz and was inhibited at the frequencies of 41.8-41.9 GHz. The effect was observed only at raised intracellular free calcium concentration and at calcium fluxes through plasma membrane. The obtained results prove the possibility of control over cell functioning by low-intensity modulated EHF EMR, presumably, manipulating by connected systems of enzyme reactions.
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[Perfluorocarbon emulsions and other corpuscular systems influence on neutrophil activity].
Influence of perfluorodecalin, perfluoromethilcyclohexylpiperidine, perfluorotributylamine emulsions on active oxygen form (AOF) generation by neutrophils has been studied. All investigated emulsions stabilized both proxanol 268 and egg yolk phospholipids inhibited PMA-stimulated neutrophil activity. Castor oil emulsion also inhibited the neutrophil activity. Neutrophil response for chemotactic peptide, was unchanged in the presence of all tested emulsions. We suppose that fast hydrophobic attachment of inert submicrone emulsion particles to cell surface provokes alteration of neutrophil plasma membrane function resulting in a decrease of AOF generation.
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[Millemetre waves inhibit the synergistic effect of calcium ionophore A23187 and phorbol ester in neutrophil respiratory burst].
The effect of extremely high frequency electromagnetic field (mm-waves) on respiratory burst of neutrophils was studied. The peritoneal evoked neutrophils of the mice (NMRI line) were used. The production of reactive oxygen species was estimated by luminol-dependent chemiluminescence technique. Cells were irradiated by the mm-waves of 41. 95 GHz in the far field zone of the channel radiator during 20 min. Absorbed energy flux density was 150 microW/cm2. The irradiation was carried out at different concentrations of calcium ionophore A23187 and then neutrophils were stimulated by phorbol 12-myristate 13-acetate (PMA) 1 microM, activator of PKC. At irradiation of neutrophils the synergistic action of A23187 and PMA was not changed at low concentration of ionophore 10 nM-0.5 microM and was suppressed at high concentrations 0.5-10 microM. The largest inhibition of about 60% was obtained at the concentration of A23187 20 microM. The effect of mm-waves was not found under exposure in Ca(2+)-free medium for all used A23187 concentrations. We suggest that the mm-wave effect on the production of reactive oxygen species by neutrophils is determined by the influx of extracellular Ca2+ and PKC.
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