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M A Poskonova

Publications and source records attributed to M A Poskonova.

At least 19 recordsLinked to original sources
PubMed1988

[Effects of acetylcholinesterase inhibitors on the process of reinnervation of the mouse skeletal muscle].

The effect of chronic in vivo injections of anticholinesterases drugs (phosphacol, proserine) on the reinnervation of m. extensor digitorum longus were studied in adult mice after motor nerve crushing. An electrophysiological technique was used to register synaptic transmission. The chronic anticholinesterases injections were shown not to change the time of initial neuro-muscular transmission reestablishment. The potentiating effects of investigated anticholinesterase agents were poorly manifested in the early period of transmission recovery. Later in the course of reinnervation the potentiating effects become pronounced and considerably (two fold) accelerate the final recovery of normal synaptic parameters and action potential generation. Long injection of drugs is not accompanied by depression of neuromuscular transmission during reinnervation.

Action Potentials↗
PubMed1986

[Acetylcholine activation of the sodium pump in frog muscle].

The effect of acetylcholine, ouabain, atropine and d-tubocurarine on the activity of K+, Na+-pump of the frog muscles was studied. Acetylcholine enhanced the activity of K+, Na+-pump, ouabain and atropine preventing the enhancement. D-tubocurarine was ineffective in blocking the ionic pump.

Acetylcholine↗
PubMed1985

[Action of cyclic nucleotide phosphodiesterase inhibitors on the acetylcholine potential].

A study was made of the action of theophylline, isobutyrylmethylxanthine and caffeine on the sensitivity of mouse diaphragmatic muscle fibers to iontophoretically applied acetylcholine (ACh). It was shown that these substances at concentrations of 5 X 10(-4) -5 X 10(-3) M reduced the amplitude and increased the duration of the ACh potential as well as accelerated desensitization of the cholinoceptor at repetitive application of ACh. As regards the action on the ACh potential amplitude two phases which differed in the time-course of development and washing were recognized: rapid and slow. Addition of dibutyryl-cAMP (5 X 10(-4) M) after theophylline (10(-3) M) potentiated the latter's action on the ACh potential amplitude but did not influence its duration and the rate of desensitization. It is assumed that the action of phosphodiesterase inhibitors on the duration of the ACh potential and the rate of desensitization is not mediated by an elevation in the muscle cAMP content. Apparently, cAMP accumulation may be responsible but for the phase of a slow decrease in the ACh potential amplitude.

1-Methyl-3-isobutylxanthine↗
PubMed1981

[Effect of calcium antagonists on action potentials of muscle fibers in the warm-blooded].

The effect of the "calcium antagonist" D600 (5.10(-6)--1.10(-4) g/ml) on the amplitude, duration and rate of the rise (Vmax) on the action potential (AP) of mouse diaphragm muscle fibers were studied. To evoke and record the AP, a standard microelectrode technique was employed with two microelectrodes being inserted into the same fiber about 50 micrometer apart. The fibers were stimulated by a single pulse or by serial ones. D600 was shown to reduce the amplitude and Vmax of AP and to increase its duration both in innervated and denervated muscle fibers. The magnitude of the membrane potential and the input resistance were not affected by D600. After denervation the sensitivity of muscle fibers to D600 fell. In the course of stimulation applied by serial pulses (1--2 Hz) instead of single ones, the inhibitory effect of D600 drastically increased. It is suggested that D600 strongly modifies the activity of fast sodium channels, the manifestations of the effect being controlled by innervation.

Action Potentials↗
PubMedDate not supplied

[The functional organization and motor innervation of the cervical skeletal muscle in mammals].

Structural and functional studies have been done on the nerve-muscle transmission in m. biventer cervicis of mouse using electrophysiological, mechanographic and microscopic techniques. It was shown that each muscle fiber has several synaptic inputs, although m. biventer cervicis is a typical phasic skeletal muscle. Usually, there is a single large synapse of the end-plate type and several small synaptic contacts. Some of the synapses investigated produce typical end-plate potential which is transformed into the action potential. Certain part of synapses are capable of producing action potentials only during facilitation of the transmission by rhythmic stimulation. In curarized preparations, supramaximum single indirect stimulus may evoke in a single point of a fiber multicomponent postsynaptic responses of various amplitude and, sometimes, of various latency. Contractile response of a single segment to a maximum direct stimulation is always higher than to an indirect one. Unusual functional properties of m. biventer cervicis are discussed in relation to peculiarities of its origin.

Animals↗
PubMedDate not supplied

[Analysis of changes in the membrane potential of denervated muscle].

Quantitative analysis of the experimental data presented in the previous paper has shown that the electrogenic pump component of the membrane potential of muscle fibres on the third day after denervation is in the average 8.7 mV, and the diffusion component--12.9 mV lower than that in the normal fibres. It is due to a decrease of the stechiometric coefficient of Na+,K+-pump at denervation from 2.15 to 1.3 and to a change of the passive ionic permeability: at denervation permeability for Na+ increases from 0.52.10(-7) to 0.67.10(-7) cm.sec-1, and for K+ decreases from 0.75.10(-5) to 0.53.10(-5) cm.sec-1.

Animals↗
PubMedDate not supplied

[Electrophysiological characteristics of muscle fibers during denervation].

Experimental material obtained on mouse extensor digitorum longus was presented concerning the dynamics of changes in the membrane potential (MP) of muscle fibres after chronic denervation (1-12 days), the effect of ouabain and increase of extracellular potassium on MP of normal and denervated muscles, changes of input resistance and volumes of muscle fibres after denervation.

Animals↗