Linked Life Data

1659226

Source:http://linkedlifedata.com/resource/pubmed/id/1659226

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5 Pt 2
pubmed:dateCreated
1991-12-23
pubmed:abstractText
Free radicals and oxidant stress have previously been shown to induce depolarization, transient action potential prolongation, and automaticity. We have investigated the ionic basis of these electrophysiological changes in isolated rabbit ventricular cells. Oxidant stress was generated by the photoactivation of rose bengal, and, in current-clamp experiments, the effects of oxidant stress on the action potential were confirmed. In voltage-clamp studies, oxidant stress decreased both inward and outward current through the inward-rectifier potassium channel, and the slope conductance (measured at the voltage-axis intercept near the resting membrane potential) was decreased from 40 +/- 8 to 25 +/- 6 nS (n = 6). Transient inward currents were induced on repolarization after a depolarizing clamp step, suggesting that the cells were calcium overloaded. In addition, oxidant stress activated a steady-state membrane conductance that showed a slight outward-going rectification and a reversal potential of approximately 0 mV. Evidence is presented to indicate that this reflects an increase in the conductance of the calcium-activated nonselective cation channel. The slope conductance of this calcium-activated channel (measured at the voltage-axis intercept) increased with prolonged exposure to oxidant stress (from 0.5 to 12 nS after 7 min), indicating that the intracellular free calcium increased gradually during the maintained application of rose bengal. These results suggest that oxidant stress depolarizes the cell membrane by reducing the inward-rectifier potassium current and by activating a calcium-activated membrane conductance. Both factors may contribute to the oxidant stress-induced changes in action potential duration and automaticity.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0002-9513
pubmed:author
pubmed:issnType
Print
pubmed:volume
261
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
H1358-65
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Effects of oxidant stress on steady-state background currents in isolated ventricular myocytes.
pubmed:affiliation
Cardiovascular Research, Rayne Institute, St. Thomas' Hospital, London, United Kingdom.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't