This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Spencer, C. I. Articles by Kozlowski, R. Z. Search for Related Content PubMed Articles by Spencer, C. I. Articles by Kozlowski, R. Z. Social Bookmarking                         What's this?

Signature Currents: A Patch-Clamp Method for Determining the Selectivity of Ion-Channel Blockers in Isolated Cardiac Myocytes

Department of Pharmacology, University of Bristol, Bristol, UK

Wataru Uchida

Department of Pharmacology, University of Oxford, Oxford, UK

Larry Turner

Department of Pharmacology, University of Oxford, Oxford, UK

Roland Z. Kozlowski

Department of Pharmacology, University of Bristol, Bristol, UK

Background: We describe a simple method using membrane potential ramps for rapidly determining the ion-channel selectivity of drugs that affect action-potential duration in iso lated cardiac myocytes. The method allows the simultaneous assay of compounds on a number of ionic currents in a single cardiac cell.

Methods: Trains of membrane potential ramps were applied from -90 to +70 mV at 0.33 Hz to obtain a consistent "signature current," in which the major individual currents involved in the cardiac action potential could be easily identified. Confirmatory experiments were per formed using known inhibitors of these currents.

Results: The identities of the currents in the signature were established by varying the concentrations of extracellular cations and by adding known ion channel blockers to super- fusion solutions. Inhibition of each current had a characteristic and reproducible effect on the overall signature current.

Conclusions: The consistent current signature in the presence and absence of blockers sug gests that this method could be used for tertiary electrophysiological evaluation of com pounds, eg, in a drug discovery program focusing on antiarrhythmic agents. The ability to assay for secondary effects of novel compounds against multiple currents in the target cell type is convenient and avoids the artefacts associated with using artificial expression systems.

Key Words: Heart • ventricular myocytes • antiarrhythmic drugs • drug screening.

Journal of Cardiovascular Pharmacology and Therapeutics, Vol. 5, No. 3, 193-201 (2000)
DOI: 10.1054/JCPT.8694


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?