| G-protein- and cAMP-dependent L-channel gating modulation: a manyfold system to control calcium entry in neurosecretory cells. | |
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MedLine Citation:
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PMID: 11680611 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Voltage-gated Ca2+ channels are crucial to the control of Ca2+ entry in neurosecretory cells. In the chromaffin cells of adrenal medulla, paracrinally or autocrinally released neurotransmitters induce profound changes in Ca2+ channel gating and Ca2+-dependent events controlling catecholamine secretion and cell activity. The generally held view of these processes is that neurotransmitter-induced modulation of the most widely expressed Ca2+ channels in these cells (N-, P/Q- and L-type) follows two distinct pathways: a direct membrane-delimited Gi/o-protein-induced inhibition of N- and P/Q-type and a remote cAMP-mediated facilitation of L-channels. Both actions depend on voltage, although with remarkably different molecular and kinetic aspects. Recent findings, however, challenge this simple scheme and suggest that L-channels do not require strong pre-pulses to be recruited or facilitated. They are available during normal depolarizations and may be tonically inhibited by Gi/o proteins activated by the released neurotransmitters. Like the N- and P/Q-channels, this autocrine modulation is localized to membrane microareas. Unlike N- and P/Q-channels, however, the inhibition of L-channels is largely independent of voltage and develops in parallel with cAMP-mediated potentiation of channel gating. As L-channels play a crucial role in the control of catecholamine release in chromaffin cells, the two opposite modulations mediated by Gi/o proteins and cAMP may represent an effective way to broaden the dynamic range of Ca2+ signals controlling exocytosis. Here, we review the basic features of this novel L-type channel inhibition comparing it to the well-established forms of L-channel potentiation and voltage-dependent facilitation. |
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Authors:
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E Carbone; V Carabelli; T Cesetti; P Baldelli; J M Hernández-Guijo; L Giusta |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Review |
Journal Detail:
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Title: Pflügers Archiv : European journal of physiology Volume: 442 ISSN: 0031-6768 ISO Abbreviation: Pflugers Arch. Publication Date: 2001 Sep |
Date Detail:
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Created Date: 2001-10-26 Completed Date: 2002-02-21 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0154720 Medline TA: Pflugers Arch Country: Germany |
Other Details:
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Languages: eng Pagination: 801-13 Citation Subset: IM |
Affiliation:
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Dipartimento di Neuroscienze, Unità di Ricerca INFM, Torino, Italy. emilio.carbone@unito.it |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Calcium / metabolism* Calcium Channels, L-Type / drug effects, physiology* Cell Membrane / physiology Chromaffin Cells / physiology Cyclic AMP / pharmacology* Electrophysiology GTP-Binding Proteins / physiology* Humans Ion Channel Gating* Neurosecretory Systems / metabolism* |
| Chemical | |
Reg. No./Substance:
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0/Calcium Channels, L-Type; 60-92-4/Cyclic AMP; 7440-70-2/Calcium; EC 3.6.1.-/GTP-Binding Proteins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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