rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1988-10-13
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pubmed:abstractText |
1. Magnocellular neurosecretory neurones were impaled in the supraoptic nucleus of perfused explants of rat hypothalamus. Membrane currents were studied at 35 degrees C using the single-microelectrode voltage-clamp technique. 2. Depolarizing voltage steps applied from -100 mV evoked a transient outward current (TOC) from a threshold of -75 mV. From this potential, the amplitude of the current increased non-linearly with voltage. 3. Following its activation TOC reached a peak within 7 ms and subsequently decayed monotonically with a time constant of 30 ms. This time constant did not vary significantly with voltage between -75 and -55 mV. 4. The TOC showed complete steady-state inactivation at potentials positive to -55 mV. Inactivation was removed by hyperpolarization, with a mid-point near -80 mV. The removal of inactivation followed a complex time course with distinct fast (tens of milliseconds) and slow (hundreds of milliseconds) components. 5. Tail current measurements revealed that the TOC equilibrium potential (ETOC) lies near -97 mV in the presence of 3 mM [K+]o. Increasing [K+]o caused a decrease of TOC amplitude and a shift in ETOC of 57 mV/log [K+]o. The TOC is therefore predominantly a K+ current. 6. The TOC was unaffected by tetraethylammonium (up to 12 mM) but was reversibly reduced by 4-aminopyridine (ca. 50% block at 1.0 mM) and dendrotoxin (ca. 50% block at 4 nM). 7. The TOC was strongly inhibited (greater than 70%) by adding Co2+ or Mn2+ (1-3 mM) or Cd2+ (50-400 microM) to Ca-containing solutions, or by removal of Ca2+ from the perfusate. These effects were not accompanied by detectable changes in threshold voltage. The amplitude of TOC was also depressed by the organic Ca2+ channel blocker methoxyverapamil (D600). Finally replacement of Ca2+ by Ba2+ in the perfusate completely and reversibly abolished the TOC. 8. These findings suggest that neurosecretory neurones of the rat supraoptic nucleus display a transient K+ current which is strongly dependent on the presence of external Ca2+. The possible role of this current is briefly discussed.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-1181381,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-1195141,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2409515,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2413964,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2416920,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2417246,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2419547,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2431384,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2432227,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2580089,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2582098,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2582115,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-2582271,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/2457699-850203
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0022-3751
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pubmed:author |
|
pubmed:issnType |
Print
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pubmed:volume |
397
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
331-47
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:2457699-Action Potentials,
pubmed-meshheading:2457699-Animals,
pubmed-meshheading:2457699-Calcium,
pubmed-meshheading:2457699-Calcium Channel Blockers,
pubmed-meshheading:2457699-Female,
pubmed-meshheading:2457699-Ion Channels,
pubmed-meshheading:2457699-Male,
pubmed-meshheading:2457699-Membrane Potentials,
pubmed-meshheading:2457699-Neurosecretory Systems,
pubmed-meshheading:2457699-Potassium,
pubmed-meshheading:2457699-Rats,
pubmed-meshheading:2457699-Rats, Inbred Strains,
pubmed-meshheading:2457699-Supraoptic Nucleus,
pubmed-meshheading:2457699-Tetrodotoxin,
pubmed-meshheading:2457699-Time Factors
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pubmed:year |
1988
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pubmed:articleTitle |
Transient calcium-dependent potassium current in magnocellular neurosecretory cells of the rat supraoptic nucleus.
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pubmed:affiliation |
Department of Pharmacology, School of Pharmacy, University of London.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
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