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Biomedical subjects

I A Shabunova

Publications and source records attributed to I A Shabunova.

7 recordsLinked to original sources
PubMed1978

On potassium functional feedback in neuromuscular junction.

The dependence of the reversal potential (Erev) of intracellular end-plate potentials (epp) on activity patterns was studied in frog neuromuscular preparations. A shift of Erev to the positive side was found with change in frequency of stimulation from 1/sec to 50/sec. This shift corresponds to the increase of potassium concentration in the synaptic cleft to 7.0 mM. The effect of potassium concentration [K+]0 in the bath solution on quantal content (m) of epp was studied. The quantity m increased when [K+]0 was varied within the range 4.7-8.7 mM; m decreased when [K+]0 was greater than 8.7 mM. Such a relationship between m and [K+]0 is accounted for by the combined effect of potassium on transmitter secretion and electrogenic processes in motor nerve terminals. The correlation between the change of m with [K+]0 and initial epp amplitudes was found and was attributed to potassium efflux from post-synaptic region in varying quantity depending on the initial epp amplitudes. A scheme of synaptic self-regulation by means of potassium feedback is suggested.

Animals↗
PubMed1977

[Pre-synaptic effect of histidine at neuromuscular junctions].

The influence of L-histidine in different concentrations (0.2--9.0mM) on synaptic processes in neuro-muscular preparations of the frog was studied using intracellular microelectrodes. The histidine caused lowering of the frequency of m. e. p. p. In the synapses with initial quantum content of e. p. p. less than 50, the increase of quantum content occurred due to rising of the available mediator level. The possibility of the transmitter release did not change. The histidine seems to participate in positive functional feedback in a neuro-muscular synapse, the feedback maybe essential for mobilization of the inactive synapses during intense muscular activity.

Animals↗
PubMed1975

[Influence of the potassium ion on function of the frog neuromuscular synapse].

Effects of different concentrations of potassium ions on function of motor neural endings were studied in the frog neuromuscular - muscular preparations. Quantitative relations between change of the muscle fibers' membrane rest potential and parameters of spontaneous or evoked release of transmitter, and the potassium ion concentration in the medium, were revealed. A positive specific effect of relatively low (about 8.7 mM) concentrations on the quantum composition of transsynaptic signals, was shown. The data obtained confirm the supposed participation of the potassium ions in reverse transsynaptic regulation of the neuromuscular - motor synapse function.

Animals↗