Linked Life Data

312322

Source:http://linkedlifedata.com/resource/pubmed/id/312322

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1979-7-16
pubmed:abstractText
1. Application of voltage clamp pulses (1--10 sec) to frog ventricular strips causes temporary changes in the extracellular K concentration. 2. The changes in the extracellular K concentration can be estimated from (a) slowly decaying post-clamp after-potentials, (b) changes in the action potential duration, and (c) measurements with a K-selective micro-electrode. 3. The depolarization of the resting potential and the shortening of the action potential are present in approximately the same proportions during voltage-clamp induced extracellular K accumulation and during perfusion with a K-ricn Ringer solution but small consistent differences are noticed. 4. The measurements of the after-potential, the action potential shortening, and the K-electrode response were analysed as indicators of extracellular K+ activity and it was concluded that the after-potential provides the most convenient and reliable estimate of the absolute magnitude of the voltage-clamp induced extracellular K accumulation. 5. The depolarizing after-potentials decay more slowly than the hyperpolarizing after-potentials but it is found that this reflects the selectivity of the membrane to K+ concentrations as predicted by the Nernst or the Goldman equations. 6. Analysis of the redistribution of accumulated K+ from the decay of the after-potential suggests that the major part of the redistribution process can be described by a single time constant (2--4 sec). A much longer time constant is required for a smaller component of the 'tail' in order to bring [K]o to the normal resting state. 7. N-shaped relations similar to the 'steady state' current-voltage relation are obtained when the post-clamp after-potential, the action potential shortening, and the K-electrode response are plotted versus the clamped membrane potential. The maxima of these curves are located around -40 mV and the minima around -20 mV. 8. In spite of a significant outward membrane current (1--1.5 microamperemeter) in the minimum region (-20 mV), the post-clamp after-potential is often hyperpolarizing in nature suggesting extracellular K depletion. 9. These findings indicate that the K efflux is lower at -20 mV than at both higher and lower potentials and suggest that the N-shape 'steady state' current-voltage relation mainly reflects the voltage dependency of the K current. 10. A theory for K accumulation in a single compartment is presented which predicts that a simple linear RC-circuit may describe the electrical response of the preparation in a limited potential range around the resting potential. The extracellular accumulation space was estimated to be 13--16% of the total volume of the preparation. It is tentatively suggested that the accumulation space is equivalent to the subendothelial fraction of the extracellular space.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-1086357, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-1123087, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-1246599, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-1252586, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-13320339, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-14192550, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-16992069, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-16992124, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-18128147, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-301933, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-308540, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-312318, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-4415829, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-4538490, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-4547276, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-4679725, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-4689624, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-4778411, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-5316660, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-5499788, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-5501007, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-558594, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-560474, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-5651377, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-5921832, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-5972158, http://linkedlifedata.com/resource/pubmed/commentcorrection/312322-6030516
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-3751
pubmed:author
pubmed:issnType
Print
pubmed:volume
286
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
83-111
pubmed:dateRevised
2010-9-2
pubmed:meshHeading
pubmed:year
1979
pubmed:articleTitle
Extracellular potassium accumulation in voltage-clamped frog ventricular muscle.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.