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rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1992-12-2
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pubmed:abstractText |
1. Merkel cells were dissociated enzymatically from the footpad epidermis of 10- to 20-day-old rats pretreated with fluorescent dye, quinacrine, for purposes of staining. The fluorescent Merkel cells had an elongated or elliptic shape in situ, yet the dissociated ones were round (7-12 microns in diameter). 2. Electrical recordings were performed in the whole-cell configuration using a conventional patch-clamp technique. The mean resting membrane potential of fluorescent Merkel cells was -54.0 mV, the value being greater than the -26.1 mV of non-fluorescent epidermal cells. No voltage-dependent channel was observed in non-fluorescent cells. 3. The Merkel cells had no Na+ spike in an external standard solution, but tetrodotoxin-resistant long-lasting action potentials were evoked by depolarization with injection of constant currents in an external solution containing Ba2+. 4. In Merkel cells under voltage clamp, depolarizing step pulses (800 ms) from a holding potential (VH) of -80 mV elicited predominantly outward K+ currents composed of transient and sustained components: the former was selectively inhibited by 4-aminopyridine (4-AP), while the latter was inhibited by both tetraethylammonium (TEA) and quinacrine. Quinacrine was more effective and selective than TEA in blocking the sustained K+ current but had no effect on the current at the low concentration (10(-7) or 3 x 10(-6) M) used for staining the Merkel cells. 5. The sustained outward K+ current (IKD) was activated at potentials more positive than -20 or -10 mV at a VH of -50 mV, at which potential the transient outward K+ channel was completely inactivated. The potential for half-inactivation in the steady-state inactivation curve for IKD was -33 mV. 6. The transient outward K+ current (IA) was activated at potentials more positive than -50 mV at a VH of -80 mV. The potential for half-inactivation in the steady-state inactivation curve for IA was -64 mV. 7. When the outward K+ currents were blocked by adding both TEA and 4-AP, only a sustained inward Ca2+ current was observed. In an external solution containing 10 mM-Ca2+, ICa was evoked by potentials more positive than -20 mV at a VH of -80 mV, and the maximum inward current appeared around +10 mV. Increases in external Ca2+ concentration ([Ca2+]o) induced a hyperbolic increase in ICa and shifted the current-voltage (I-V) relationship along the voltage axis in a more positive direction. Saturation of ICa occurred at about 25 mM [Ca2+]o.(ABSTRACT TRUNCATED AT 400 WORDS)
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-17734,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-1974040,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2213587,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2417192,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2451017,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2454284,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2457185,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2457683,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2458454,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2554221,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2580085,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-2580089,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-3055053,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-3187043,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-3485791,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-3685745,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-469273,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-4974746,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-5575340,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6086899,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6090654,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6097667,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6137503,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6257896,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6270629,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6831531,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-6854332,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-7069629,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-7280690,
http://linkedlifedata.com/resource/pubmed/commentcorrection/1331421-79446
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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 |
May
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pubmed:issn |
0022-3751
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
450
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
143-62
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pubmed:dateRevised |
2010-9-7
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pubmed:meshHeading |
pubmed-meshheading:1331421-Animals,
pubmed-meshheading:1331421-Calcium,
pubmed-meshheading:1331421-Calcium Channels,
pubmed-meshheading:1331421-Cells, Cultured,
pubmed-meshheading:1331421-Epidermis,
pubmed-meshheading:1331421-Membrane Potentials,
pubmed-meshheading:1331421-Potassium,
pubmed-meshheading:1331421-Potassium Channels,
pubmed-meshheading:1331421-Quinacrine,
pubmed-meshheading:1331421-Rats,
pubmed-meshheading:1331421-Rats, Inbred Strains
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pubmed:year |
1992
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pubmed:articleTitle |
Voltage-dependent currents in isolated single Merkel cells of rats.
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pubmed:affiliation |
Department of Neurophysiology, Tohoku University School of Medicine, Sendai, Japan.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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