Ca2+ dependence and pharmacology of large-conductance K+ channels in nonlabor and labor human uterine myocytes

Raheela N. Khan, Stephen K. Smith, J. J. Morrison, M. L. Ashford

    Research output: Contribution to journalArticlepeer-review

    69 Citations (Scopus)

    Abstract

    Two populations, Ca(2+)-dependent (BKCa) and Ca(2+)-independent K+ (BK) channels of large conductance were identified in inside-out patches of nonlabor and labor freshly dispersed human pregnant myometrial cells, respectively. Cell-attached recordings from nonlabor myometrial cells frequently displayed BKCa channel openings characterized by a relatively low open-state probability, whereas similar recordings from labor tissue displayed either no channel openings or consistently high levels of channel activity that often exhibited clear, oscillatory activity. In inside-out patch recordings, Ba2+ (2-10 mM), 4-aminopyridine (0.1-1 mM), and Shaker B inactivating peptide ("ball peptide") blocked the BKCa channel but were much less effective on BK channels. Application of tetraethylammonium to inside-out membrane patches reduced unitary current amplitude of BKCa and BK channels, with dissociation constants of 46 mM and 53 microM, respectively. Tetraethylammonium applied to outside-out patches decreased the unitary conductance of BKCa and BK channels, with dissociation constants of 423 and 395 microM, respectively. These results demonstrate that the properties of human myometrial large-conductance K+ channels in myocytes isolated from laboring patients are significantly different from those isolated from nonlaboring patients.
    Original languageEnglish
    Pages (from-to)C1721-31
    JournalAmerican Journal of Physiology: Cell Physiology
    Volume273
    Issue number5
    Publication statusPublished - Nov 1997

    Keywords

    • Ion Channel Gating
    • Reference Values
    • Calcium
    • Charybdotoxin
    • Labor, Obstetric
    • Humans
    • Large-Conductance Calcium-Activated Potassium Channels
    • Potassium Channels, Calcium-Activated
    • Potassium Channels
    • Pregnancy
    • Patch-Clamp Techniques
    • Muscle, Smooth
    • Cells, Cultured
    • Barium
    • Membrane Potentials
    • 4-Aminopyridine
    • Tetraethylammonium
    • Myometrium
    • Female

    Fingerprint Dive into the research topics of 'Ca2+ dependence and pharmacology of large-conductance K+ channels in nonlabor and labor human uterine myocytes'. Together they form a unique fingerprint.

    Cite this