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2. Interaction of glutamate- and adenosine-induced decrease of acetylcholine quantal release at frog neuromuscular junction
- Creator:
- Svatopluk Adámek, Shakirzyanova, A. V., Malomouzh, A. I., Naumenko, N. V., and Vyskočil, F.
- Format:
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, endplate potentials, guanylyl cyclase, carbacholine, ATP, NO, 14, and 612
- Language:
- English
- Description:
- In a frog neuromuscular preparation of m. sartorius, glutamate had a reversible dose-dependent inhibitory effect on both spontaneous miniature endplate potentials (MEPP) and nerve stimulation-evoked endplate potentials (EPP). The effect of glutamate on MEPP and EPP is caused by the activation of metabotropic glutamate receptors, as it was eliminated by MCPG, an inhibitor of group I metabotropic glutamate receptors. The depression of evoked EPP, but not MEPP frequency was removed by inhibiting the NO production in the muscle by L-NAME and by ODQ that inhibits the soluble NO-sensitive guanylyl cyclase. The glutamate-induced depression of the frequency of spontaneous MEPP is apparently not caused by the stimulation of the NO cascade. The particular glutamate-stimulated NO cascade affecting the evoked EPP can be down-regulated also by adenosine receptors, as the glutamate and adenosine actions are not additive and application of adenosine partially prevents the further decrease of quantal content by glutamate. On the other hand, there is no obvious interaction between the glutamatemediated inhibition of EPP and inhibitory pathways triggered by carbacholine and ATP. The effect of glutamate on the evoked EPP release might be due to NO-mediated modulation (phosphorylation) of the voltage-dependent Ca2+ channels at the presynaptic release zone that are necessary for evoked quantal release and open during EPP production., S. Adámek ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Non-quantal acetylcholine release at the neuromuscular junction
- Creator:
- František Vyskočil, Malomouzh, A. I., and Nikolsky, E. E.
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, acetylcholin, synapse, oxid dusnatý, hibernace, physiology, acetylcholine, synapses, nitric oxide, hibernation, non-quantal release, neuromuscular junction, desensitization, resting membrane potential, choline transporter, vesicular ACh transporter, anticholinesterase, N-acetylaspartylglutamate, miniature endplate potential, 14, and 612
- Language:
- English
- Description:
- There are two principal mechanisms of acetylcholine (ACh) release from the resting motor nerve terminal: quantal and non-quantal (NQR); the former being only a small fraction of the total, at least at rest. In the present article we summarize basic research about the NQR that is undoubtedly an important trophic factor during endplate development and in adult neuromuscular contacts. NQR helps to eliminate the polyneural innervation of developing muscle fibers, ensures higher excitability of the adult subsynaptic membrane by surplus polarization and protects the RMP from depolarization by regulating the NO cascade and chloride transport. It shortens the endplate potentials by promoting postsynaptic receptor desensitization when AChE is inhibited during anti-AChE poisoning. In adult synapses, it can also activate the electrogenic Na+/K+-pump, change the degree of synchronization of quanta released by the nerve stimulation and affects the contractility of skeletal muscles., F. Vyskočil, A. I. Malomouzh, E. E. Nikolsky., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Voltage-dependent P/Q-type calcium channels at the frog neuromuscular junction
- Creator:
- Nurullin, L. F., Mukhitov, A. R., Tsentsevytsky, A. N., Petrova, N. V., Samigullin, D. V., Malomouzh, A. I., Bukharaeva, E. A., František Vyskočil, and Nikolsky, E. E.
- Format:
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, nervosvalový přenos, acetylcholin, neuromuscular transmission, acetylcholine, motor nerve terminal, acetylcholine release, N- and P/Q-type calcium channels, 14, and 612
- Language:
- English
- Description:
- It is well known that antagonists of N-type voltage-gated calcium channels inhibit the evoked quan tal release of acetylcholine in amphibian neuromuscular synapses. This, however, does not exclude the functional expression of other types of voltage-gated calcium channels in these nerve terminals. Using immunocytochemistry, we detected the expression of the α1A subunit of P/Q-type calcium channels (that is otherwise typical of mammalian motor nerve endings) in the frog neuromuscular junction. In addition, we demonstrated that the P/Q-type channel blocker ω-agatoxin IVA (20 nM) reduced the action potential- induced calcium transient and significantly decreased both spontaneous and evoked mediator release. Our data indicates the functional expression of P/Q-type calcium channels in the frog motor nerve ending which participate in acetylcholine release., L. F. Nurullin ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public