A fast transient outward current in the rat sympathetic neurone studied under voltage-clamp conditions
Post-ganglionic neurones of the isolated rat superior cervical ganglion were voltage clamped at 37 degrees C using separate intracellular voltage and current micro-electrodes. Control experiments in current clamp suggested that the neurone is electrotonically compact, the soma and the proximal dendr...
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| Veröffentlicht in: | The Journal of physiology 1985-01, Vol.358 (1), p.91-108 |
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| description | Post-ganglionic neurones of the isolated rat superior cervical ganglion were voltage clamped at 37 degrees C using separate
intracellular voltage and current micro-electrodes. Control experiments in current clamp suggested that the neurone is electrotonically
compact, the soma and the proximal dendritic membranes being under good spatial voltage uniformity. Depolarizing voltage steps
from membrane potentials near -50 mV evoked: (i) a voltage-dependent inward Na+ current, (ii) an inward Ca2+ current, (iii)
a voltage-dependent outward K+ current, (iv) a Ca2+-activated K+ outward current. Depolarizations from holding potentials
more negative than -60 mV elicited, besides the currents mentioned above, a fast transient outward current IA which peaked
in 1-2.5 ms and then decayed to zero following an exponential time course. The IA current was shown to be primarily, if not
exclusively, carried by K+. It was unaffected by removal of external Ca2+ or addition of Cd2+ and was weakly blocked by tetraethylammonium
ions and partially by 4-aminopyridine. The IA current showed a linear instantaneous current-voltage relationship. Its activation
ranged from -60 to 0 mV with a mid-point at -30 mV. The A conductance could be described in terms of a simple Boltzmann distribution
for a single gating particle with a valency of +3. Both the development and removal of inactivation followed a single exponential
time course with a voltage-dependent time constant which was large near the resting potential (42 ms at -70 mV) and small
(11 ms) near -100 and -40 mV. Steady-state inactivation h infinity ranged from -100 to -50 mV, with a mid-point at -78 mV,
suggesting that approximately 50% of the IA channels are available at the physiological resting potential. Action potentials
elicited from various holding potentials showed maximal repolarization rates dependent on the holding potential itself. This
voltage dependence was found to be in reasonably good agreement with that of h infinity curve. These data are consistent with
the view that in the rat sympathetic neurone, under physiological conditions, it is the IA current rather than the delayed
outward current that is responsible for the fast action potential repolarization. |
| doi_str_mv | 10.1113/jphysiol.1985.sp015542 |
| format | Article |
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intracellular voltage and current micro-electrodes. Control experiments in current clamp suggested that the neurone is electrotonically
compact, the soma and the proximal dendritic membranes being under good spatial voltage uniformity. Depolarizing voltage steps
from membrane potentials near -50 mV evoked: (i) a voltage-dependent inward Na+ current, (ii) an inward Ca2+ current, (iii)
a voltage-dependent outward K+ current, (iv) a Ca2+-activated K+ outward current. Depolarizations from holding potentials
more negative than -60 mV elicited, besides the currents mentioned above, a fast transient outward current IA which peaked
in 1-2.5 ms and then decayed to zero following an exponential time course. The IA current was shown to be primarily, if not
exclusively, carried by K+. It was unaffected by removal of external Ca2+ or addition of Cd2+ and was weakly blocked by tetraethylammonium
ions and partially by 4-aminopyridine. The IA current showed a linear instantaneous current-voltage relationship. Its activation
ranged from -60 to 0 mV with a mid-point at -30 mV. The A conductance could be described in terms of a simple Boltzmann distribution
for a single gating particle with a valency of +3. Both the development and removal of inactivation followed a single exponential
time course with a voltage-dependent time constant which was large near the resting potential (42 ms at -70 mV) and small
(11 ms) near -100 and -40 mV. Steady-state inactivation h infinity ranged from -100 to -50 mV, with a mid-point at -78 mV,
suggesting that approximately 50% of the IA channels are available at the physiological resting potential. Action potentials
elicited from various holding potentials showed maximal repolarization rates dependent on the holding potential itself. This
voltage dependence was found to be in reasonably good agreement with that of h infinity curve. These data are consistent with
the view that in the rat sympathetic neurone, under physiological conditions, it is the IA current rather than the delayed
outward current that is responsible for the fast action potential repolarization.</description><identifier>ISSN: 0022-3751</identifier><identifier>EISSN: 1469-7793</identifier><identifier>DOI: 10.1113/jphysiol.1985.sp015542</identifier><identifier>PMID: 2580089</identifier><identifier>CODEN: JPHYA7</identifier><language>eng</language><publisher>Oxford: The Physiological Society</publisher><subject>4-Aminopyridine ; action potential ; Action Potentials - drug effects ; Aminopyridines - pharmacology ; Animals ; Biological and medical sciences ; Calcium - physiology ; Electric Conductivity ; Female ; Fundamental and applied biological sciences. Psychology ; Ganglia, Sympathetic - physiology ; In Vitro Techniques ; Ion Channels - physiology ; ions ; Membrane Potentials ; neurons ; Neurons - physiology ; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ ; Potassium - physiology ; Rats ; Rats, Inbred Strains ; superior cervical ganglion ; Time Factors ; Vertebrates: nervous system and sense organs</subject><ispartof>The Journal of physiology, 1985-01, Vol.358 (1), p.91-108</ispartof><rights>1985 The Physiological Society</rights><rights>1985 INIST-CNRS</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c5721-9ce907f88df957ac78c50fcf9756c092a61e8c4fc698299796626b1aac9b10c33</citedby></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC1193333/pdf/$$EPDF$$P50$$Gpubmedcentral$$H</linktopdf><linktohtml>$$Uhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC1193333/$$EHTML$$P50$$Gpubmedcentral$$H</linktohtml><link.rule.ids>230,314,723,776,780,881,1411,4010,27900,27901,27902,45550,45551,53766,53768</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=9253811$$DView record in Pascal Francis$$Hfree_for_read</backlink><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/2580089$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Belluzzi, O</creatorcontrib><creatorcontrib>Sacchi, O</creatorcontrib><creatorcontrib>Wanke, E</creatorcontrib><title>A fast transient outward current in the rat sympathetic neurone studied under voltage-clamp conditions</title><title>The Journal of physiology</title><addtitle>J Physiol</addtitle><description>Post-ganglionic neurones of the isolated rat superior cervical ganglion were voltage clamped at 37 degrees C using separate
intracellular voltage and current micro-electrodes. Control experiments in current clamp suggested that the neurone is electrotonically
compact, the soma and the proximal dendritic membranes being under good spatial voltage uniformity. Depolarizing voltage steps
from membrane potentials near -50 mV evoked: (i) a voltage-dependent inward Na+ current, (ii) an inward Ca2+ current, (iii)
a voltage-dependent outward K+ current, (iv) a Ca2+-activated K+ outward current. Depolarizations from holding potentials
more negative than -60 mV elicited, besides the currents mentioned above, a fast transient outward current IA which peaked
in 1-2.5 ms and then decayed to zero following an exponential time course. The IA current was shown to be primarily, if not
exclusively, carried by K+. It was unaffected by removal of external Ca2+ or addition of Cd2+ and was weakly blocked by tetraethylammonium
ions and partially by 4-aminopyridine. The IA current showed a linear instantaneous current-voltage relationship. Its activation
ranged from -60 to 0 mV with a mid-point at -30 mV. The A conductance could be described in terms of a simple Boltzmann distribution
for a single gating particle with a valency of +3. Both the development and removal of inactivation followed a single exponential
time course with a voltage-dependent time constant which was large near the resting potential (42 ms at -70 mV) and small
(11 ms) near -100 and -40 mV. Steady-state inactivation h infinity ranged from -100 to -50 mV, with a mid-point at -78 mV,
suggesting that approximately 50% of the IA channels are available at the physiological resting potential. Action potentials
elicited from various holding potentials showed maximal repolarization rates dependent on the holding potential itself. This
voltage dependence was found to be in reasonably good agreement with that of h infinity curve. These data are consistent with
the view that in the rat sympathetic neurone, under physiological conditions, it is the IA current rather than the delayed
outward current that is responsible for the fast action potential repolarization.</description><subject>4-Aminopyridine</subject><subject>action potential</subject><subject>Action Potentials - drug effects</subject><subject>Aminopyridines - pharmacology</subject><subject>Animals</subject><subject>Biological and medical sciences</subject><subject>Calcium - physiology</subject><subject>Electric Conductivity</subject><subject>Female</subject><subject>Fundamental and applied biological sciences. Psychology</subject><subject>Ganglia, Sympathetic - physiology</subject><subject>In Vitro Techniques</subject><subject>Ion Channels - physiology</subject><subject>ions</subject><subject>Membrane Potentials</subject><subject>neurons</subject><subject>Neurons - physiology</subject><subject>Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ</subject><subject>Potassium - physiology</subject><subject>Rats</subject><subject>Rats, Inbred Strains</subject><subject>superior cervical ganglion</subject><subject>Time Factors</subject><subject>Vertebrates: nervous system and sense organs</subject><issn>0022-3751</issn><issn>1469-7793</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>1985</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNqNkU-P0zAQxS0EWkrhI4B8QKu9pHiS2o4vSNWK5Y9WgsNytlzHabxK7WA7W-Xb46jdAhfAF2s8v3njp4fQGyArAKje3Q_dFK3vVyBquooDAUrX5RO0gDUTBeeieooWhJRlUXEKz9GLGO8JgYoIcYEuSloTUosFaje4VTHhFJSL1riE_ZgOKjRYjyHMtXU4dQYHlXCc9oPKRbIaOzMG7wyOaWysafDoGhPwg--T2plC92o_YO1dY5P1Lr5Ez1rVR_PqdC_R95sPd9efituvHz9fb24LTXkJhdBGEN7WddMKypXmtaak1a3glGkiSsXA1HrdaibqUgguGCvZFpTSYgtEV9USvT_qDuN2bxqdDQTVyyHYvQqT9MrKPzvOdnLnHySAqOazRJcngeB_jCYmubdRm75XzvgxSs7ImjLOM3j1VxA4EcBrEOyfmnNieTtkkB1BHXyMwbTnjwORc-ryMXU5py4fU8-Dr3-3fR47xZz7b099FbXq2xy2tvGMiZJWNcz7N0fsYHsz_edyeffl2_xQ0WwWfpnt7K472GDkcSp6bU2aZMYkyAz-BCcB3Tg</recordid><startdate>19850101</startdate><enddate>19850101</enddate><creator>Belluzzi, O</creator><creator>Sacchi, O</creator><creator>Wanke, E</creator><general>The Physiological Society</general><general>Blackwell</general><scope>IQODW</scope><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7TK</scope><scope>8FD</scope><scope>FR3</scope><scope>M7Z</scope><scope>P64</scope><scope>7X8</scope><scope>5PM</scope></search><sort><creationdate>19850101</creationdate><title>A fast transient outward current in the rat sympathetic neurone studied under voltage-clamp conditions</title><author>Belluzzi, O ; Sacchi, O ; Wanke, E</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c5721-9ce907f88df957ac78c50fcf9756c092a61e8c4fc698299796626b1aac9b10c33</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>1985</creationdate><topic>4-Aminopyridine</topic><topic>action potential</topic><topic>Action Potentials - drug effects</topic><topic>Aminopyridines - pharmacology</topic><topic>Animals</topic><topic>Biological and medical sciences</topic><topic>Calcium - physiology</topic><topic>Electric Conductivity</topic><topic>Female</topic><topic>Fundamental and applied biological sciences. Psychology</topic><topic>Ganglia, Sympathetic - physiology</topic><topic>In Vitro Techniques</topic><topic>Ion Channels - physiology</topic><topic>ions</topic><topic>Membrane Potentials</topic><topic>neurons</topic><topic>Neurons - physiology</topic><topic>Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ</topic><topic>Potassium - physiology</topic><topic>Rats</topic><topic>Rats, Inbred Strains</topic><topic>superior cervical ganglion</topic><topic>Time Factors</topic><topic>Vertebrates: nervous system and sense organs</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Belluzzi, O</creatorcontrib><creatorcontrib>Sacchi, O</creatorcontrib><creatorcontrib>Wanke, E</creatorcontrib><collection>Pascal-Francis</collection><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>Neurosciences Abstracts</collection><collection>Technology Research Database</collection><collection>Engineering Research Database</collection><collection>Biochemistry Abstracts 1</collection><collection>Biotechnology and BioEngineering Abstracts</collection><collection>MEDLINE - Academic</collection><collection>PubMed Central (Full Participant titles)</collection><jtitle>The Journal of physiology</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Belluzzi, O</au><au>Sacchi, O</au><au>Wanke, E</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>A fast transient outward current in the rat sympathetic neurone studied under voltage-clamp conditions</atitle><jtitle>The Journal of physiology</jtitle><addtitle>J Physiol</addtitle><date>1985-01-01</date><risdate>1985</risdate><volume>358</volume><issue>1</issue><spage>91</spage><epage>108</epage><pages>91-108</pages><issn>0022-3751</issn><eissn>1469-7793</eissn><coden>JPHYA7</coden><abstract>Post-ganglionic neurones of the isolated rat superior cervical ganglion were voltage clamped at 37 degrees C using separate
intracellular voltage and current micro-electrodes. Control experiments in current clamp suggested that the neurone is electrotonically
compact, the soma and the proximal dendritic membranes being under good spatial voltage uniformity. Depolarizing voltage steps
from membrane potentials near -50 mV evoked: (i) a voltage-dependent inward Na+ current, (ii) an inward Ca2+ current, (iii)
a voltage-dependent outward K+ current, (iv) a Ca2+-activated K+ outward current. Depolarizations from holding potentials
more negative than -60 mV elicited, besides the currents mentioned above, a fast transient outward current IA which peaked
in 1-2.5 ms and then decayed to zero following an exponential time course. The IA current was shown to be primarily, if not
exclusively, carried by K+. It was unaffected by removal of external Ca2+ or addition of Cd2+ and was weakly blocked by tetraethylammonium
ions and partially by 4-aminopyridine. The IA current showed a linear instantaneous current-voltage relationship. Its activation
ranged from -60 to 0 mV with a mid-point at -30 mV. The A conductance could be described in terms of a simple Boltzmann distribution
for a single gating particle with a valency of +3. Both the development and removal of inactivation followed a single exponential
time course with a voltage-dependent time constant which was large near the resting potential (42 ms at -70 mV) and small
(11 ms) near -100 and -40 mV. Steady-state inactivation h infinity ranged from -100 to -50 mV, with a mid-point at -78 mV,
suggesting that approximately 50% of the IA channels are available at the physiological resting potential. Action potentials
elicited from various holding potentials showed maximal repolarization rates dependent on the holding potential itself. This
voltage dependence was found to be in reasonably good agreement with that of h infinity curve. These data are consistent with
the view that in the rat sympathetic neurone, under physiological conditions, it is the IA current rather than the delayed
outward current that is responsible for the fast action potential repolarization.</abstract><cop>Oxford</cop><pub>The Physiological Society</pub><pmid>2580089</pmid><doi>10.1113/jphysiol.1985.sp015542</doi><tpages>18</tpages><oa>free_for_read</oa></addata></record> |
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| ispartof | The Journal of physiology, 1985-01, Vol.358 (1), p.91-108 |
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| source | MEDLINE; Wiley Online Library Journals Frontfile Complete; EZB-FREE-00999 freely available EZB journals; PubMed Central; Alma/SFX Local Collection |
| subjects | 4-Aminopyridine action potential Action Potentials - drug effects Aminopyridines - pharmacology Animals Biological and medical sciences Calcium - physiology Electric Conductivity Female Fundamental and applied biological sciences. Psychology Ganglia, Sympathetic - physiology In Vitro Techniques Ion Channels - physiology ions Membrane Potentials neurons Neurons - physiology Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ Potassium - physiology Rats Rats, Inbred Strains superior cervical ganglion Time Factors Vertebrates: nervous system and sense organs |
| title | A fast transient outward current in the rat sympathetic neurone studied under voltage-clamp conditions |
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