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L D Karpenko

Publications and source records attributed to L D Karpenko.

15 recordsLinked to original sources
PubMed1993

[The effect of a magnesium-free solution on neuronal activity in the snail].

This investigation has revealed that application of magnesium-free medium to snail brain preparations results in the development of paroxysmal depolarization shifts (PDSs) and depolarizing afterpotentials in some neurons. The neurons studied were classified by their responses to low extracellular magnesium as active or passive. In the active neurons, typical PDSs observed were characterized by plateau potential with complete inactivation of the spike generating mechanism. In the passive neurons the magnitude of PDSs was sufficient to inactivate the mechanism of spike generation. The PDSs were synchronized in synaptically unconnected neurons. The results show that the snail brain preparation immersed to the magnesium-free solution is a suitable model of experimental epilepsy, since Helix nerve cells are easy to identify.

Animals↗
PubMed1993

[The effect of a magnesium-free solution on the parameters of the spontaneous excitatory postsynaptic potentials in identified snail neurons].

This investigation has revealed that application of magnesium-free medium to snail brain preparation changes the parameters of excitatory input to the identified neurons of the snail: the distribution of amplitude and intervals between EPSP. The other parameters (time to peak level and duration of EPSP) remained unaltered. It is concluded that spontaneous firing activity of initially silent neurons in magnesium-free solution develops as a result of increased efficiency of excitatory input.

Animals↗
PubMed1980

[Localization of neurons innervating edible snail columellar muscles].

The location of large and small nerve cells taking part in the realization of the protective reflex in the snail subesophageal nerve ganglion circle was studied by the method modified of the retrograde transport of cobalt ions. The data were compared with those of the previous electrophysiological studies of the protective reflex mechanism. A conclusion is made that this response is realized by a system consisting of 9 large and 60-80 small nerve cells.

Animals↗
PubMedDate not supplied

[The effect of the delta sleep peptide and serotonin on the neurons of the snail].

The present paper describes the results concerning the influence of delta sleep-inducing peptide (DSIP) and serotonin (5-HT) on electrophysiological properties of the identified snail neurons. The experiments were performed on semi-intact preparations from Helix lucorum L. DSIP inhibited spontaneously active neurons and reduced responses of silent cells to depolarizing currents and tactile stimuli. DSIP effects were dose-dependent. 5-HT excited neurons in question. DSIP and 5-HT had the mutually opposite effects on the identified neurons. The results suggest that DSIP can directly affect the snail neurons not via serotoninergic system. Hyperpolarization effect of DSIP can be due to the enhancement of Cl conduction or to the changes in adenylatcyclase system activity. Alternatively DSIP can influence the process of synaptic transmission.

Animals↗