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Biomedical subjects

G G Kurchavyĭ

Publications and source records attributed to G G Kurchavyĭ.

At least 19 recordsLinked to original sources
PubMed2006

[Three types of miniature inhibitory potentiaes in the frog spinal cord motoneurons: the possibility of GABA and glycine co-release].

Miniature inhibitory postsynaptic potentials (mlPSPs) were recorded from motoneurons of the frog isolated spinal cord after blocking action potentials and ionotropic glutamate receptors (TTX 1 mcm: CNQX 25 mcm, D-AP5 50 mcm). Three types of mlPSPs were selected by their time characteristics) fast, slow and mlPSPs with two decay time constants. We classified 8.7% of mlPSPs as dual-component, 64.5% as fast mlPSPs, and 26.8% as slow mlPSPs. The GABA(A)R blocker bicuculline (20 mcm) diminished the number of the slow and dual-component events while the number of mlPSP with a fast kinetics was increased. The GlyR antagonist strychnine (1 mcm) reduced the frequency of fast mlPSPs and increased this parameter of slow mlPSPs. These data suggest existence of three different mlPSP groups distinguished by their kinetics and sensitivity to receptor antagonists: fast events mediated by glycine, slow events mediated by GABA and dual-component mlPSPs corresponding to glycine and GABA co-release.

Action Potentials↗
PubMed1988

[Properties of the response of frog motoneurons to glutamate application].

The reversal potential (E) of the glutamate response produced by iontophoretically applied glutamate and that of the EPSP's recorded from three synaptic inputs produced by reticular formation (RF), dorsal roots (DS), and microstimulation of presynaptic terminals (PT) at the point of glutamate application were compared at the same motoneuron of the isolated frog spinal cord using current-chop technique. Following Cs injection the glutamate response and EPSP's were reversed. Different points of glutamate application were tested. Mean values of E were: Eglu = -16.9 +/- 1.7 mV (n = 13), EPT = -15.1 +/- 1.4 mV (n = 13), ERF = -6.8 +/- 1.7 mV (n = 13), EOR = -9.8 +/- 1.8 mV (n = 6). The summation of the glutamate responses and EPSP was close to linear. Increase of the input conductance did not exceed 10%. The results obtained suggest that glutamate induces depolarization via the receptors of the postsynaptic membrane and may serve as a neurotransmitter in all of the studied inputs.

Animals↗
PubMed1986

[Reversal potential of the EPSP of frog motoneurons].

The current-chop technique has shown that I-V characteristic of the membrane are nonlinear in lumbar motoneurons of isolated perfused frog spinal cord. Input resistance of the membrane decreased with depolarization when constant current was applied during 0.1-1.0 s. However, injection of current 40-60 nA during 1-2 min led to an increase of the membrane resistance to the initial value. As a result the membrane potential could be shifted to the positive level up to +50 mV and more. Monosynaptic excitatory postsynaptic potentials evoked by stimulation of the brainstem or by microstimulation of ventrolateral tract fibres were found to reverse completely at a positive level of the membrane potential. In most cases the reversal potentials ranged between 0 mV and -10 mV.

Animals↗
PubMed1980

[Properties of the excitatory postsynaptic currents in the cat motor neurons].

Monosynaptic supraspinal and la excitatory postsynaptic current (e. p. s. c.) recorded with the aid of voltage clamp technique at different levels of MP, revealed characteristics as follows: peak amplitude 2--18 nA, rise time 0.3--0.5 msec, half-width 0.5--1.0 msec; extrapolated reversal potential +70-+100 mV. Slow residual current (1--4 nA) followed the e. p. s. c. E. p. s. c. and e. p. s. p. s were discussed considering the current-voltage relation and analog model.

Animals↗
PubMedDate not supplied

[The heterogeneity of the excitatory synaptic inputs in the spinal motor neurons of the frog Rana ridibunda].

The synaptic responses induced in motoneurones by the stimulations of the dorsal root (DR), single afferent fibres and reticular formation (RF) were intracellularly recorded in the isolated frog spinal cord. It was shown that argiopine (the selective blocker of glutamate receptors of non-NMDA type) in concentrations ranging from 3.10(-7) to 1.10(-5) M effectively suppressed the di- and polysynaptic, but not the monosynaptic components of EPSP's induced by DR stimulation. The initial reaction to argiopine consisted of the increase of this monosynaptic component of EPSP. In the same concentrations range, argiopine reduced both mono- and polysynaptic EPSP, evoked by RF stimulation. 2-amino-phosphonovaleric acid (1.10(-4) M) did not affect, whereas the kinurenate (1--2.10(-3) M) completely blocked the amplitude of all kinds of synaptic responses. The various effects of argiopine on the responses induced by microstimulation of presynaptic nerve terminals were observed. The data obtained speak in favour of heterogeneity of monosynaptic excitatory inputs in the motoneurones of frog spinal cord. Being the glutamatergic by nature, the inputs differ in the properties of postsynaptic receptors. All of these receptors concerning to non NMDA-type can be divided to argiopine-sensitive and argiopine-resistant. The first seem to be involved in the monosynaptic connections of RF and the second--in those of primary afferents with motoneurones.

2-Amino-5-phosphonovalerate↗