| Forskolin and phorbol esters decrease the same K+ conductance in cultured oligodendrocytes. | |
MedLine Citation:
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PMID: 3216367 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Cultured ovine oligodendrocytes (OLGs) express a number of voltage-dependent potassium currents after they attach to a substratum and as they begin to develop processes. At 24-48 hours following plating, an outward potassium current can be identified that represents a composite response of a rapidly inactivating component and a steady-state or noninactivating component. After 4-7 days in culture, OLGs also develop an inward rectifier current. We studied the effects of forskolin and phorbol 12-myristate 13-acetate (PMA) on OLG outward currents. These compounds are known to alter the myelinogenic metabolism of OLGs. PMA, an activator of protein kinase C (PK-C), has been shown to enhance myelin basic protein phosphorylation while forskolin acting on adenylate cyclase, and thereby increasing cAMP, inhibits it. Both forskolin and PMA increase the phosphorylation of 2'3'-cyclic nucleotide phosphodiesterase, an OLG/myelin protein. We found that forskolin decreased the steady-state outward current at 120 mV by 10% at 100 nM, and by 72% at 25 microM from a holding potential of -80 mV. The time course of inactivation of the peak currents was decreased, affecting both the fast and slow time constants. There was no significant change in the steady-state parameters of current activation and inactivation. The effect of forskolin was attenuated when the adenylate cyclase inhibitor adenosine (2 mM) was present in the intracellular/pipette filling solution. The results of PMA experiments were similar to those obtained with forskolin. Whereas the amplitude of the currents in the presence of PMA was reduced by 28% at 1.5 nM and 60% and 600 nM, the decay phase of the peak currents was less affected. The PMA effect could still be seen when the intracellular Ca2+ was reduced to less than or equal to 10 nM with 5 mM BAPTA, but was inhibited when the cells were pre-exposed to 50 microM psychosine, a PK-C inhibitor. It is postulated that the potassium currents in OLG can be physiologically modulated by two distinct second-messenger systems, perhaps converging at the level of a common phosphorylated enzyme or regulatory protein. |
Authors:
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B Soliven; S Szuchet; B G Arnason; D J Nelson |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of membrane biology Volume: 105 ISSN: 0022-2631 ISO Abbreviation: J. Membr. Biol. Publication Date: 1988 Oct |
Date Detail:
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Created Date: 1989-03-09 Completed Date: 1989-03-09 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0211301 Medline TA: J Membr Biol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 177-86 Citation Subset: IM |
Affiliation:
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Department of Neurology, University of Chicago, Illinois 60637. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cells, Cultured Electric Conductivity Electrophysiology Forskolin / pharmacology* Membrane Potentials / drug effects Neuroglia / drug effects* Oligodendroglia / cytology, drug effects*, physiology Phorbol Esters / pharmacology* Potassium / physiology* Second Messenger Systems Tetradecanoylphorbol Acetate / pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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R0 1 GM36823/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Phorbol Esters; 16561-29-8/Tetradecanoylphorbol Acetate; 66428-89-5/Forskolin; 7440-09-7/Potassium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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