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Titolo:
Number of K-Ca channels underlying spontaneous miniature outward currents (SMOCs) in mudpuppy cardiac neurons
Autore:
Scornik, FS; Merriam, LA; Parsons, RL;
Indirizzi:
Univ Vermont, Coll Med, Dept Anat & Neurobiol, Burlington, VT 05405 USA Univ Vermont Burlington VT USA 05405 Neurobiol, Burlington, VT 05405 USA
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 1, volume: 85, anno: 2001,
pagine: 54 - 60
SICI:
0022-3077(200101)85:1<54:NOKCUS>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
BULLFROG SYMPATHETIC NEURONS; SMOOTH-MUSCLE CELLS; ACTIVATED POTASSIUM CHANNELS; ROOT GANGLION-CELLS; PARASYMPATHETIC NEURONS; INTRACELLULAR CA2+; CALCIUM-RELEASE; SPARKS; MEMBRANE; HYPERPOLARIZATIONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
40
Recensione:
Indirizzi per estratti:
Indirizzo: Parsons, RL Univ Vermont, Coll Med, Dept Anat & Neurobiol, Burlington, VT 05405 USA Univ Vermont Burlington VT USA 05405 Burlington, VT 05405 USA
Citazione:
F.S. Scornik et al., "Number of K-Ca channels underlying spontaneous miniature outward currents (SMOCs) in mudpuppy cardiac neurons", J NEUROPHYS, 85(1), 2001, pp. 54-60

Abstract

Spontaneous miniature outward currents (SMOCs) in parasympathetic neurons from mudpuppy cardiac ganglia are caused by activation of TEA-and iberiotoxin-sensitive, Ca2+-dependent K+ (BK) channels. Previously we reported that SMOCs are activated by Ca2+-induced Ca2+ release (CICR) from caffeine- and ryanodine-sensitive intracellular Ca2+ stores. In the present study, we analyzed the single channel currents that contribute to SMOC generation in mudpuppy cardiac neurons. The slope conductance of BK channels, determined from the I-V relationship of single-channel currents recorded with cell-attached patches in physiological K+ concentrations, was 84 pS. The evidence supporting the identity of this channel as the channel involved in SMOC generation was its sensitivity to internal Ca2+, external TEA, and caffeine. In cell-attached patch recordings, 166 muM TEA applied in the pipette reduced single-channel current amplitude by 32%, and bath-applied caffeine increased BK channel activity. The ratio between the averaged SMOC amplitude and the single-channel current amplitude was used to estimate the average number ofchannels involved in SMOC generation. The estimated number of channels involved in generation of an averaged SMOC ranged from 18 to 23 channels. We also determined that the Po of the BK channels at the peak of a SMOC remainsconstant at voltages more positive than -20 mV, suggesting that the transient rise in intracellular Ca2+ from ryanodine-sensitive intracellular stores in the vicinity of the BK channel reached concentrations most likely exceeding 40 muM.

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Documento generato il 04/12/20 alle ore 13:22:08