Effect of isoprenaline on If current in latent pacemaker cells isolated from cat right atrium: ruptured vs. perforated patch whole-cell recording methods

Zhengfeng Zhou, Stephen L. Lipsius

    Research output: Contribution to journalArticle

    17 Scopus citations

    Abstract

    Whole-cell recording techniques were used to study the time-dependent inward current activated on hyperpolarization (If) and its response to isoprenaline in latent atrial pacemaker cells isolated from cat right atrium. To determine whether the response to isoprenaline depended on the type of recording method, we analysed If using either a standard ruptured-patch, or a nystatinperforated-patch, whole-cell recording method. All cells beat rhythmically at 35°C and exhibited normal pacemaker action potentials and If current, regardless of the recording method. With the ruptured-patch method, pacemaker action potentials ceased activity within a few minutes and If amplitude decreased "ran down" to 74% of control within 10 min of rupturing the patch. Isoprenaline (1 μM) elicited variable changes in If amplitude among different latent pacemaker cells resulting in no net change in mean current amplitude (n=6). In addition, isoprenaline failed to change the voltage dependence of the If activation curve. On the other hand, using a nystatin-perforated-patch method, pacemaker action potentials and If exhibited no significant changes over the same 10 min period. Under these conditions, isoprenaline consistently increased If in all cells studied (+90% at -80 mV; n=8), and increased the spontaneous rate of pacemaker action potentials by 58±7% (n=5). Moreover, isoprenaline elicited a significant positive shift (+11 mV) in the half-maximal activation voltage of the If activation curve (n=3). We conclude that latent atrial pacemakers consistently exhibit If current, and that isoprenaline consistently elicits an increase in If amplitude. Variabilities in the response of If to isoprenaline may result from the loss of internal constituents when using the ruptured-patch, whole-cell recording method.

    Original languageEnglish (US)
    Pages (from-to)442-447
    Number of pages6
    JournalPflügers Archiv European Journal of Physiology
    Volume423
    Issue number5-6
    DOIs
    StatePublished - Jun 1 1993

    Keywords

    • Electrophysiology
    • Nystatin
    • Single cells
    • Voltage clamp

    ASJC Scopus subject areas

    • Physiology
    • Clinical Biochemistry
    • Physiology (medical)

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