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Titolo:
DYNAMIC REGULATION OF CALCIUM INFLUX BY G-PROTEINS, ACTION-POTENTIAL WAVE-FORM, AND NEURONAL FIRING FREQUENCY
Autore:
PARK D; DUNLAP K;
Indirizzi:
TUFTS UNIV,SCH MED,DEPT PHYSIOL,136 HARRISON AVE BOSTON MA 02111 TUFTS UNIV,SCH MED,DEPT PHYSIOL BOSTON MA 02111 TUFTS UNIV,SCH MED,DEPT NEUROSCI BOSTON MA 02111
Titolo Testata:
The Journal of neuroscience
fascicolo: 17, volume: 18, anno: 1998,
pagine: 6757 - 6766
SICI:
0270-6474(1998)18:17<6757:DROCIB>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
CHICK SENSORY NEURONS; DORSAL RAPHE NEURONS; N-TYPE; CHANNEL CURRENTS; INDEPENDENT MECHANISMS; SYMPATHETIC NEURONS; BINDING PROTEINS; GENE-EXPRESSION; CA2+ CHANNELS; MODULATION;
Keywords:
CA2+ CHANNEL; G-PROTEIN-COUPLED RECEPTOR; ACTION POTENTIAL; MODULATION; CA2+ INFLUX; FREQUENCY-DEPENDENT EFFECTS; G-PROTEIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
56
Recensione:
Indirizzi per estratti:
Citazione:
D. Park e K. Dunlap, "DYNAMIC REGULATION OF CALCIUM INFLUX BY G-PROTEINS, ACTION-POTENTIAL WAVE-FORM, AND NEURONAL FIRING FREQUENCY", The Journal of neuroscience, 18(17), 1998, pp. 6757-6766

Abstract

The time course of Ca2+ channel activation and the amplitude and rateof change of Ca2+ influx are primarily controlled by membrane voltage. G-protein-coupled signaling pathways, however, modulate the efficacyof membrane voltage on channel gating. To study the interactions of membrane potential and G-proteins on Ca2+ influx in a physiological context, we have measured N-type Ca2+ currents evoked by action potentialwaveforms in voltage-clamped chick dorsal root ganglion neurons. We have quantified the effect of varying action potential waveforms and frequency on the shape of Ca2+ current in the presence and absence of transmitters (GABA or norepinephrine) that inhibit N current. Our results demonstrate that both the profile of Ca2+ entry and the time course and magnitude of its transmitter-induced inhibition are sensitive functions of action potential waveform and frequency. Increases in action potential duration enhance total Ca2+ entry, but they also prolong andblunt Ca2+ signals by slowing influx rate and reducing peak amplitude. Transmitter-mediated inhibition of Ca2+ entry is most robust with short-duration action potentials and decreases exponentially with increasing duration. Increases in action potential frequency promote a voltage-dependent inactivation of Ca2+ influx. In channels exposed to GABA or norepinephrine, however, this inactivation is counteracted by a time- and frequency-dependent relief of modulation. Thus, multiple stimuli are integrated by Ca2+ channels, tuning the profile of influx in a changing physiological environment. Such variations are likely to be significant for the control of Ca2+-dependent cellular responses in all tissues.

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Documento generato il 03/04/20 alle ore 03:57:24