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Article: Characterization of an ultrarapid delayed rectifier potassium channel involved in canine atrial repolarization

TitleCharacterization of an ultrarapid delayed rectifier potassium channel involved in canine atrial repolarization
Authors
Issue Date1996
PublisherWiley-Blackwell Publishing Ltd.. The Journal's web site is located at http://www.wiley.com/bw/journal.asp?ref=0022-3751
Citation
Journal Of Physiology, 1996, v. 496 n. 3, p. 647-662 How to Cite?
Abstract1. Depolarizing pulses positive to 0 mV elicit a transient outward current (I(to)) and a sustained 'pedestal' current in canine atrial myocytes. The pedestal current was highly sensitive to 4-aminopyridine (4-AP) and TEA, with 50% inhibitory concentrations (EC 50) of 5.3 ± 0.7 and 307 ± 25 μM, respectively. When the pedestal current was separated from I(to) with prepulses or by studying current sensitive to 10 mM TEA, it showed very rapid activation and deactivation. We therefore designated the current I(Kur,d), for 'ultrarapid delayed rectifier, dog'. I(Kur,d) inactivation was bi-exponential, with mean time constants of 609 ± 91 and 5563 ± 676 ms during a 20 s pulse to +40 mV. 2. The reversal potential of I(Kur,d) tail currents are dependent on extracellular potassium concentration ([K +](o); slope, 54.7 mV decade -1). The envelope of tails test was satisfied and the current inwardly rectified at ≤ +40 mV. The current was insensitive to E-4031, dendrotoxin and chloride substitution, but was inhibited by barium, with an EC 50 of 1.65 mM. Lanthanum ions caused a positive shift in voltage dependence without producing direct inhibition. 3. Single-channel activity was observed in cell-attached, inside-out and outside-out patches. Upon depolarization from -50 to +30 mV, single channels had similar time constants and [K +](o) dependence to whole-cell current. Channel open probability (P(o)) increased with depolarization in a saturable fashion and the P(o)-voltage relation had a half-activation voltage and slope factor similar to whole-cell I(Kur,d). 4. Unitary channel current was linearly related to depolarization potential to +40 mV; at more positive potentials, inward rectification occurred. The unitary conductance was 20.3 and 35.5 pS for an [K +](o) of 5.4 and 130 mM, respectively. Single-channel activity was strongly inhibited by 50 μM 4-AP or 10 mM TEA. Both 4-AP and TEE decreased open time, suggesting open-channel block. 5. Selective inhibition of I(Kur,d) with 50 μM 4-AP or 0.3-5 mM TEA prolonged canine atrial action potentials, indicating that I(Kur,d) contributes to canine atrial repolarization. The single-channel and macroscopic properties of I(Kur,d) have many similarities to those of currents carried by Kv3.1 cloned channels and our findings thus suggest a possible role for Kv3.1 channels in cardiac repolarization.
Persistent Identifierhttp://hdl.handle.net/10722/162153
ISSN
2015 Impact Factor: 4.731
2015 SCImago Journal Rankings: 2.670
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorYue, Len_US
dc.contributor.authorFeng, Jen_US
dc.contributor.authorLi, GRen_US
dc.contributor.authorNattel, Sen_US
dc.date.accessioned2012-09-05T05:17:41Z-
dc.date.available2012-09-05T05:17:41Z-
dc.date.issued1996en_US
dc.identifier.citationJournal Of Physiology, 1996, v. 496 n. 3, p. 647-662en_US
dc.identifier.issn0022-3751en_US
dc.identifier.urihttp://hdl.handle.net/10722/162153-
dc.description.abstract1. Depolarizing pulses positive to 0 mV elicit a transient outward current (I(to)) and a sustained 'pedestal' current in canine atrial myocytes. The pedestal current was highly sensitive to 4-aminopyridine (4-AP) and TEA, with 50% inhibitory concentrations (EC 50) of 5.3 ± 0.7 and 307 ± 25 μM, respectively. When the pedestal current was separated from I(to) with prepulses or by studying current sensitive to 10 mM TEA, it showed very rapid activation and deactivation. We therefore designated the current I(Kur,d), for 'ultrarapid delayed rectifier, dog'. I(Kur,d) inactivation was bi-exponential, with mean time constants of 609 ± 91 and 5563 ± 676 ms during a 20 s pulse to +40 mV. 2. The reversal potential of I(Kur,d) tail currents are dependent on extracellular potassium concentration ([K +](o); slope, 54.7 mV decade -1). The envelope of tails test was satisfied and the current inwardly rectified at ≤ +40 mV. The current was insensitive to E-4031, dendrotoxin and chloride substitution, but was inhibited by barium, with an EC 50 of 1.65 mM. Lanthanum ions caused a positive shift in voltage dependence without producing direct inhibition. 3. Single-channel activity was observed in cell-attached, inside-out and outside-out patches. Upon depolarization from -50 to +30 mV, single channels had similar time constants and [K +](o) dependence to whole-cell current. Channel open probability (P(o)) increased with depolarization in a saturable fashion and the P(o)-voltage relation had a half-activation voltage and slope factor similar to whole-cell I(Kur,d). 4. Unitary channel current was linearly related to depolarization potential to +40 mV; at more positive potentials, inward rectification occurred. The unitary conductance was 20.3 and 35.5 pS for an [K +](o) of 5.4 and 130 mM, respectively. Single-channel activity was strongly inhibited by 50 μM 4-AP or 10 mM TEA. Both 4-AP and TEE decreased open time, suggesting open-channel block. 5. Selective inhibition of I(Kur,d) with 50 μM 4-AP or 0.3-5 mM TEA prolonged canine atrial action potentials, indicating that I(Kur,d) contributes to canine atrial repolarization. The single-channel and macroscopic properties of I(Kur,d) have many similarities to those of currents carried by Kv3.1 cloned channels and our findings thus suggest a possible role for Kv3.1 channels in cardiac repolarization.en_US
dc.languageengen_US
dc.publisherWiley-Blackwell Publishing Ltd.. The Journal's web site is located at http://www.wiley.com/bw/journal.asp?ref=0022-3751en_US
dc.relation.ispartofJournal of Physiologyen_US
dc.subject.mesh4-Aminopyridine - Pharmacologyen_US
dc.subject.meshAnimalsen_US
dc.subject.meshDelayed Rectifier Potassium Channelsen_US
dc.subject.meshDogsen_US
dc.subject.meshFemaleen_US
dc.subject.meshHeart - Physiologyen_US
dc.subject.meshHeart Atriaen_US
dc.subject.meshIon Channel Gatingen_US
dc.subject.meshMaleen_US
dc.subject.meshMembrane Potentials - Drug Effects - Physiologyen_US
dc.subject.meshMicroelectrodesen_US
dc.subject.meshPatch-Clamp Techniquesen_US
dc.subject.meshPotassium - Pharmacologyen_US
dc.subject.meshPotassium Channels - Drug Effects - Physiologyen_US
dc.subject.meshPotassium Channels, Voltage-Gateden_US
dc.subject.meshProbabilityen_US
dc.subject.meshTetraethylammoniumen_US
dc.subject.meshTetraethylammonium Compounds - Pharmacologyen_US
dc.subject.meshTime Factorsen_US
dc.titleCharacterization of an ultrarapid delayed rectifier potassium channel involved in canine atrial repolarizationen_US
dc.typeArticleen_US
dc.identifier.emailLi, GR:grli@hkucc.hku.hken_US
dc.identifier.authorityLi, GR=rp00476en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.pmid8930833-
dc.identifier.scopuseid_2-s2.0-0029992590en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0029992590&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume496en_US
dc.identifier.issue3en_US
dc.identifier.spage647en_US
dc.identifier.epage662en_US
dc.identifier.isiWOS:A1996VT70600006-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridYue, L=7101974873en_US
dc.identifier.scopusauthoridFeng, J=7403884361en_US
dc.identifier.scopusauthoridLi, GR=7408462932en_US
dc.identifier.scopusauthoridNattel, S=36048738800en_US

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