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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions |
umls-concept:C0000925,
umls-concept:C0007961,
umls-concept:C0026649,
umls-concept:C0034650,
umls-concept:C0039476,
umls-concept:C0205266,
umls-concept:C0231530,
umls-concept:C0449432,
umls-concept:C1179435,
umls-concept:C1280500,
umls-concept:C1304649,
umls-concept:C1524073,
umls-concept:C1546426,
umls-concept:C1548280,
umls-concept:C1548799,
umls-concept:C1705248,
umls-concept:C1706211,
umls-concept:C1707455
|
| pubmed:issue |
2
|
| pubmed:dateCreated |
1991-11-26
|
| pubmed:abstractText |
Charge movements were measured in frog intact fibers with the three-microelectrode technique and in cut fibers with the double Vaseline gap technique. At 13-14 degrees C, the ON segments of charge movement records from both preparations showed an early I beta component and a late I gamma hump component. When an intact fiber was cooled to 4-7 degrees C, the time-to-peak of I gamma (tp,gamma) was prolonged, but I gamma still appeared as a hump. Q-V plots from intact fibers at 4-7 degrees C were fitted with a sum of two Boltzmann distribution functions (method 1). The more steeply voltage-dependent component, identified with Q gamma, accounted for 32.1% (SEM 2.2%) of the total charge. This fraction was larger than the 22.6% (SEM 1.5%) obtained by separating the ON currents with a sum of two kinetic functions (method 2). The total charge in cut fibers stretched to a sarcomere length of 3.5 microns at 13-14 degrees C was separated into Q beta and Q gamma by methods 1 and 2. The fraction of Q gamma in the total charge was 51.3% (SEM 1.7%) and 53.7% (SEM 1.8%), respectively, suggesting that cut fibers have a larger proportion of Q gamma:Q beta than intact fibers. When cut fibers were stretched to a sarcomere length of 4 microns, the proportion of Q gamma:Q beta was unchanged. Between 4 and 13 degrees C, the Q10 of l/tp,gamma in intact fibers was 2.33 (SEM 0.33) and that of 1/tau beta was less than 1.44 (SEM 0.04), implying that the kinetics of I gamma has a steeper temperature dependence than the kinetics of I beta. When cut fibers were cooled from 14 to 6 degrees C, I gamma in the ON segment generally became too broad to be manifested as a hump. In a cut fiber in which I gamma was manifested as a hump, the Q10 of l/tp,gamma was 2.08 and that of l/tau beta was less than 1.47. Separating the Q-V plots from cut fibers at different temperatures by method 1 showed that the proportion of Q gamma:Q beta was unaffected by temperature change. The appearance of I gamma humps at low temperatures in intact fibers but generally not in cut fibers suggests an intrinsic difference between the two fiber preparations.
|
| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Aug
|
| pubmed:issn |
0022-1295
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
98
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
287-314
|
| pubmed:dateRevised |
2008-11-20
|
| pubmed:meshHeading |
pubmed-meshheading:1940852-Animals,
pubmed-meshheading:1940852-Electrophysiology,
pubmed-meshheading:1940852-Homeostasis,
pubmed-meshheading:1940852-Kinetics,
pubmed-meshheading:1940852-Models, Biological,
pubmed-meshheading:1940852-Muscle Contraction,
pubmed-meshheading:1940852-Muscles,
pubmed-meshheading:1940852-Physical Stimulation,
pubmed-meshheading:1940852-Rana temporaria,
pubmed-meshheading:1940852-Temperature
|
| pubmed:year |
1991
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| pubmed:articleTitle |
Comparison of charge movement components in intact and cut twitch fibers of the frog. Effects of stretch and temperature.
|
| pubmed:affiliation |
Department of Physiology and Biophysics, Indiana University Medical Center, Indianapolis 46223.
|
| pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|