Modelling endplate currents: dependence on quantum secretion probability and decay of miniature current

Giniatullin, Rashid; Kheeroug, L. S.; Vyskočil, F.

doi:10.1007/bf00196832

Cited by 32 publications

(25 citation statements)

References 30 publications

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“…The effect of TPC growth prolongation was analyzed using the convolution method [8,14]. This helped us to evaluate the changes in the time course of AC secretion, which is slower in the presence of BK than in the control (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Bradykinin effect on conduction of rhythmic series of pulses through the neuromuscular synapse

1998

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Bradykinin did not change the amplitude and duration of growth and decrease of individual currents of the terminal plate, but potentiated the depression of amplitudes of consecutive currents during stimulation of the motor nerve at a frequency of 10-60 Hz under conditions of two-electrode fixation of potential on a frog neuromuscular preparation. The origin of this effect is presynaptic, because it does not depend on the activity of acetylcholinesterase and is associated with a longer increase in the terminal plate currents which are synchronous with the amplitude depression. The deconvolution method revealed a slower kinetics of the mediator secretion under the effect of bradykinin. Bradykinin impairs the conduction of rhythmic pulse series through the synapse by augmenting the asynchronism of the transmitter quantum secretion from the motor nerve endings, which may underlie the development of muscular asthenia observed in inflammatory and allergic reactions.Key Words: synapse; plasticity; bradykinin; secretion; acetylcholine Bradykinin (BK) is a humeral factor whose concentration increases in damaged tissues and during allergic and inflammatory reactions [12]. BK effects on smooth muscular cells and sympathetic neurons, which it activates through the second messengers diacylglycerol and inositol trisphosphate with subsequent increase in the concentration of intracellular calcium, are studied in detail [4]. There are no published data on the effect of BK on the peripheral neuromuscular system; experiments in a cell culture of the glioma synaptically connected to the skeletal muscular fibers revealed an inhibitory effect of this agent on synaptie transfer because of suppressed acetylcholino (AC) secretion [13]. If a similar effect of BK develops in the neuromuscular system in rive, it may lead to myasthenia in inflammatory and allergic diseases. Therefore we investigated the effect of BK on the amplitude and time course of currents in the terminal plate (TPC) during rhythmic stiDepartment of Normal Physiology, Kazan State Medical University mutation of the motor nerve under conditions of intact high (close to the normal)level of induced secretion of AC. MATERIALS AND METHODSExperiments were carried out on a neuromuscular sciatic nerve--musculus sartorius preparation of Rana temporaria at 20-21~ The muscle was perfused with Ringer's solution containing (in mmolfliter): 115 NaCI, 2.5 KC1, 1.8 CaC 89 and 2.4 NaHCO v pH 7.3. In order to preserve induced secretion of the mediator at the level close to the normal, muscular contractions were blocked by transverse section of the muscle. TPC were recorded using two-electrode fixation of the membrane potential with a numbering of 5-20 i~see/point. The TPC parameters were calculated on a PC. The time course of secretion during a single synaptic transfer was evaluated by the deconvolution method [8,14]. The methods were described in detail previously [1][2][3].

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Section: Resultsmentioning

confidence: 99%

“…The TPC parameters were calculated on a PC. The time course of secretion during a single synaptic transfer was evaluated by the deconvolution method [8,14]. The methods were described in detail previously [1][2][3].…”

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confidence: 99%

Bradykinin effect on conduction of rhythmic series of pulses through the neuromuscular synapse

1998

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“…Mathematical modeling of the process of uniquanturn EPC summation has been used to show that alternations in the degree of synchronism of the synaptic effects evoked by a single action potential can modulate synaptic transmission even when other parameters of postsynaptic responses remain unchanged [2][3][4]. Mathematical simulation showed that changes in the time course of quanta secretion affect the rise time of multiquantum signals.…”

Section: Introductionmentioning

confidence: 99%

Modulation of the time course of evoked quantum release in the nerve-muscle junction

2000

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“…Modeling of the summation of single-quantum EPC from fluctuations in the magnitude of their true synaptic delays, demonstrated a significant role for the degree of synchronization of mediator quantum release in producing the amplitude-time characteristics of multiquantum EPC [3,17,33].…”

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Synchronization of evoked secretion of quanta of mediator as a mechanism facilitating the action of sympathomimetics

Bukharaeva

Kim

Никольский

et al. 2000

Neurosci Behav Physiol

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Experiments on frog neuromuscular junction preparations with extracellular recording of nerve terminal action potentials and single-quantum end-plate currents (EPC) were used to assess the time course of evoked quantum secretion of mediator by analyzing histograms of the distribution of true synaptic delays. These studies showed that noradrenaline, isoproterenol, and dobutamine change the kinetics of secretion of quanta, leading to synchronization of the process of mediator release; substances blocking beta-adrenoceptors (atenolol, propranolol) blocked this effect. Clonidine and phenylephrine, which activate alpha-receptors, had no effect on the kinetics of secretion, while the alpha-blocker phentolamine had no effect on the synchronizing action of noradrenaline. Reconstruction of multiquantum EPC from changes in the level of synchronization in the release of individual quanta, showed that EPC amplitude increased in response to noradrenaline by 17%, and that this was due only to alterations in the time course of secretion. These data led to the conclusion that there is a special presynaptic mechanism which facilitates the action of sympathomimetics, acting via beta-adrenoceptors.

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Modelling endplate currents: dependence on quantum secretion probability and decay of miniature current

Cited by 32 publications

References 30 publications

Bradykinin effect on conduction of rhythmic series of pulses through the neuromuscular synapse

Bradykinin effect on conduction of rhythmic series of pulses through the neuromuscular synapse

Modulation of the time course of evoked quantum release in the nerve-muscle junction

Synchronization of evoked secretion of quanta of mediator as a mechanism facilitating the action of sympathomimetics

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