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Titolo:
Inhibition of large-conductance Ca2+-activated K+ channels in hippocampal neurons by toosendanin
Autore:
Wang, ZF; Shi, YL;
Indirizzi:
Chinese Acad Sci, Shanghai Inst Biol Sci, Key Lab Neurobiol, Inst Physiol,Shanghai 200031, Peoples R China Chinese Acad Sci Shanghai Peoples R China 200031 200031, Peoples R China
Titolo Testata:
NEUROSCIENCE
fascicolo: 1, volume: 104, anno: 2001,
pagine: 41 - 47
SICI:
0306-4522(2001)104:1<41:IOLCKC>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
ACTIVATED POTASSIUM CHANNELS; RAT; CALCIUM; MICRODIALYSIS; CULTURE; LEVEL; CELLS;
Keywords:
triterpenoid derivative; inhibitor; patch clamp; single-channel recording; K+ current; neurotransmitter release;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
27
Recensione:
Indirizzi per estratti:
Indirizzo: Shi, YL Chinese Acad Sci, Shanghai Inst Biol Sci, Key Lab Neurobiol, Inst Physiol,320 Yue Yang Rd, Shanghai 200031, Peoples R China Chinese Acad Sci 320 Yue Yang Rd Shanghai Peoples R China 200031
Citazione:
Z.F. Wang e Y.L. Shi, "Inhibition of large-conductance Ca2+-activated K+ channels in hippocampal neurons by toosendanin", NEUROSCIENC, 104(1), 2001, pp. 41-47

Abstract

The effect of toosendanin, a selective presynaptic blocker acid effective antibotulismic agent, on large-conductance Ca2+-activated K+ channels was studied in inside-out patches of pyramidal neurons freshly isolated from thehippocampal CAI region of the rat. Toosendanin (1 X 10(-6) g/ml similar to1 X 10(-4) g/ml) was found to inhibit large-conductance Ca2+-activated K- channels by reducing its open probability significantly in a concentration-dependent manner. although the effective concentration of toosendanin was lower in a symmetrical K+ (150 mM) solution than under asymmetrical conditions (changing K- concentration in pipette solution to 5 mM). The action was partially reversible by washing. By decreasing the slow open time constant,toosendanin shortened the open dwell time of large-conductance Ca activated Ki channels in a dose-dependent manner. A dose-dependent reduction of unitary current amplitude of the channel was detected after toosendanin perfusion, On elevating the intracellular free calcium concentration from 1 to 10muM, a similar effect on large-conductance Ca2+-activared K+ channels by toosendanin was also observed, but its efficacy wan diminished. These results show that toosendanin inhibits large-conductance Ca2+-activated K+ channels in hippocampal neurons by reducing the open probability andunitary current amplitude of the channel. and that Ca2+ interferes with the effect. These data provide an explanation for toosendanin-induced facilitation of neurotransmitter release and the antibotulismic effect of the drug. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.

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Documento generato il 05/04/20 alle ore 03:48:09