| Effects of membrane potential on just detectable movement in rat skeletal muscle: effects of denervation. | |
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MedLine Citation:
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PMID: 8006957 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The potential, Vt, at which a brief test depolarization first elicited movement was determined using two-microelectrode point voltage clamp. We expected that inactivation of excitation-contraction coupling at conditioning potentials between -60 and 0 mV would shift Vt to more positive potentials, and that fibers would become inactivatable with less conditioning depolarization in EDL than soleus. The curve relating Vt to conditioning potential had a negative slope (which was insensitive to addition of 1 mM cobalt or replacement of calcium with 20 mM CaEGTA) between -60 and -35 mV and a steep positive slope with further depolarization Unexpectedly, fibers became inactivatable with less conditioning depolarization in soleus than in EDL when Vt was measured with 50 msec test pulses. However, the positive shift in Vt became less steep as test pulse duration lengthened in soleus fibers. When Vt obtained with test pulses approaching rheobase (10 msec in EDL and 500 msec in soleus) was compared, EDL fibers became inactive with less conditioning depolarization than soleus fibers. The increase in Vt became steeper with 1 mM cobalt or 20 mM CaEGTA and was shifted to more positive potentials by denervation in soleus fibers. We conclude that inactivation (i) does not strongly influence threshold contractions at conditioning potentials between -60 and -40 mV and (ii) influences Vt between -40 and 0 mV in a manner that depends on test pulse duration. |
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Authors:
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M F Patterson; A F Dulhunty |
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Publication Detail:
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Type: In Vitro; Journal Article |
Journal Detail:
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Title: The Journal of membrane biology Volume: 138 ISSN: 0022-2631 ISO Abbreviation: J. Membr. Biol. Publication Date: 1994 Mar |
Date Detail:
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Created Date: 1994-07-15 Completed Date: 1994-07-15 Revised Date: 2006-11-15 |
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: 197-207 Citation Subset: IM; S |
Affiliation:
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Muscle Research Group, JCSMR, Australian National University, Canberra. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Calcium / metabolism, pharmacology Electric Stimulation Electrophysiology Male Membrane Potentials / drug effects Muscle Contraction / drug effects, physiology* Muscle Denervation Muscles / drug effects, innervation, physiology* Potassium / pharmacology Rats Rats, Wistar |
| Chemical | |
Reg. No./Substance:
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7440-09-7/Potassium; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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