Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1991-5-6
pubmed:abstractText
Skeletal muscles of adult mice and frogs were dissociated enzymatically and prepared for patch-clamping within less than 6 h. Outside-out patches were superfused with repetitive pulses of acetylcholine (ACh) with switching times of about 0.2 ms. Peak responses were reached within 1 ms. In mouse muscle the average channel conductance was 65 pS and the average open time 1 ms (20 degrees C). Between 1 and 10 microM ACh, the peak responses increased proportional to the second to third power of the ACh concentration, and less steeply between 10 and 1000 microM ACh. The apparent Km of the dose-response curve was about 100 microM. After the peak, channel opening probability declined with time constants decreasing from about 1 s with 1 microM ACh to 15-50 ms with 1 mM ACh. After 100 ms desensitization the channel opening had decreased to less than 1/300 peak value. The rate of desensitization increased with rising temperature, with Q10 values of 1.7-2.5 between 10 and 30 degrees C. The desensitization characteristics of channels from frog muscle were similar to that from mice. With pulses of 100 microM ACh the channels opened with a probability of 0.55, the open probability declining with a time constant of about 60 ms and dropping to less than 0.001 after 300 ms. The results support the view that three binding steps of ACh are necessary for opening of the channel. Desensitization in the presence of high ACh concentrations is slower than the decay of synaptic currents.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0031-6768
pubmed:author
pubmed:issnType
Print
pubmed:volume
417
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
509-16
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Steep concentration dependence and fast desensitization of nicotinic channel currents elicited by acetylcholine pulses, studied in adult vertebrate muscle.
pubmed:affiliation
Physiologisches Institut, Technischen Universität München, Federal Republic of Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't