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Molecular physiology and pharmacology of HERG. Single-channel currents and block by dofetilide.
Circulation. 1996 Nov 15; 94(10):2572-9.Circ

Abstract

BACKGROUND

The human ether-a-go-go-related gene (HERG) is one locus for the hereditary long-QT syndrome. A hypothesis is that HERG produces the repolarizing cardiac potassium current IKr with the consequence that mutations in HERG prolong the QT interval by reducing IKr. The elementary properties of HERG are unknown, and as a test of the hypothesis that HERG produces IKr, we compared their elementary properties.

METHODS AND RESULTS

We injected HERG cRNA into Xenopus oocytes and measured currents from single channels or current variance from the noise produced by ensembles of channels recorded from macro patches. Single-channel conductance was dependent on the extracellular potassium concentration ([K]o). At physiological [K]o, it was 2 picosiemens (pS), and at 100 mmol/L [K]o, it was 10 pS. Openings occurred in bursts with a mean duration of 26 ms at -100 mV. Mean open time was 3.2 ms and closed times were 1.0 and 26 ms. In excised macro patches, HERG currents were blocked by the class III antiarrhythmic drug dofetilide, with an IC50 of 35 nmol/L. Dofetilide block was slow and greatly attenuated at positive potentials at which HERG rectifies.

CONCLUSIONS

The microscopic physiology of HERG and IKr is similar, consistent with HERG being an important component of IKr. The pharmacology is also similar; dofetilide appears to primarily block activated channels and has a much lower affinity for closed and inactivated channels.

Authors+Show Affiliations

Rammelkamp Center for Research, Case Western Reserve University, Cleveland, Ohio 44109-1998, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8921803

Citation

Kiehn, J, et al. "Molecular Physiology and Pharmacology of HERG. Single-channel Currents and Block By Dofetilide." Circulation, vol. 94, no. 10, 1996, pp. 2572-9.
Kiehn J, Lacerda AE, Wible B, et al. Molecular physiology and pharmacology of HERG. Single-channel currents and block by dofetilide. Circulation. 1996;94(10):2572-9.
Kiehn, J., Lacerda, A. E., Wible, B., & Brown, A. M. (1996). Molecular physiology and pharmacology of HERG. Single-channel currents and block by dofetilide. Circulation, 94(10), 2572-9.
Kiehn J, et al. Molecular Physiology and Pharmacology of HERG. Single-channel Currents and Block By Dofetilide. Circulation. 1996 Nov 15;94(10):2572-9. PubMed PMID: 8921803.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Molecular physiology and pharmacology of HERG. Single-channel currents and block by dofetilide. AU - Kiehn,J, AU - Lacerda,A E, AU - Wible,B, AU - Brown,A M, PY - 1996/11/15/pubmed PY - 1996/11/15/medline PY - 1996/11/15/entrez SP - 2572 EP - 9 JF - Circulation JO - Circulation VL - 94 IS - 10 N2 - BACKGROUND: The human ether-a-go-go-related gene (HERG) is one locus for the hereditary long-QT syndrome. A hypothesis is that HERG produces the repolarizing cardiac potassium current IKr with the consequence that mutations in HERG prolong the QT interval by reducing IKr. The elementary properties of HERG are unknown, and as a test of the hypothesis that HERG produces IKr, we compared their elementary properties. METHODS AND RESULTS: We injected HERG cRNA into Xenopus oocytes and measured currents from single channels or current variance from the noise produced by ensembles of channels recorded from macro patches. Single-channel conductance was dependent on the extracellular potassium concentration ([K]o). At physiological [K]o, it was 2 picosiemens (pS), and at 100 mmol/L [K]o, it was 10 pS. Openings occurred in bursts with a mean duration of 26 ms at -100 mV. Mean open time was 3.2 ms and closed times were 1.0 and 26 ms. In excised macro patches, HERG currents were blocked by the class III antiarrhythmic drug dofetilide, with an IC50 of 35 nmol/L. Dofetilide block was slow and greatly attenuated at positive potentials at which HERG rectifies. CONCLUSIONS: The microscopic physiology of HERG and IKr is similar, consistent with HERG being an important component of IKr. The pharmacology is also similar; dofetilide appears to primarily block activated channels and has a much lower affinity for closed and inactivated channels. SN - 0009-7322 UR - https://www.unboundmedicine.com/medline/citation/8921803/Molecular_physiology_and_pharmacology_of_HERG__Single_channel_currents_and_block_by_dofetilide_ L2 - http://www.ahajournals.org/doi/full/10.1161/01.cir.94.10.2572?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -