{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T23:23:59Z","timestamp":1790378639629,"version":"4.1.0"},"reference-count":30,"publisher":"American Physiological Society","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Cell Physiology"],"published-print":{"date-parts":[[1997,11,1]]},"abstract":"<jats:p> Two populations, Ca<jats:sup>2+<\/jats:sup>-dependent (BK<jats:sub>Ca<\/jats:sub>) and Ca<jats:sup>2+<\/jats:sup>-independent K<jats:sup>+<\/jats:sup> (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 BK<jats:sub>Ca<\/jats:sub> 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, Ba<jats:sup>2+<\/jats:sup> (2\u201310 mM), 4-aminopyridine (0.1\u20131 mM), and Shaker B inactivating peptide (\u201cball peptide\u201d) blocked the BK<jats:sub>Ca<\/jats:sub> channel but were much less effective on BK channels. Application of tetraethylammonium to inside-out membrane patches reduced unitary current amplitude of BK<jats:sub>Ca<\/jats:sub> and BK channels, with dissociation constants of 46 mM and 53 \u03bcM, respectively. Tetraethylammonium applied to outside-out patches decreased the unitary conductance of BK<jats:sub>Ca<\/jats:sub> and BK channels, with dissociation constants of 423 and 395 \u03bcM, respectively. These results demonstrate that the properties of human myometrial large-conductance K<jats:sup>+<\/jats:sup>channels in myocytes isolated from laboring patients are significantly different from those isolated from nonlaboring patients. <\/jats:p>","DOI":"10.1152\/ajpcell.1997.273.5.c1721","type":"journal-article","created":{"date-parts":[[2017,12,24]],"date-time":"2017-12-24T17:14:53Z","timestamp":1514135693000},"page":"C1721-C1731","source":"Crossref","is-referenced-by-count":58,"title":["Ca<sup>2+<\/sup> dependence and pharmacology of large-conductance K<sup>+<\/sup>  channels in nonlabor and labor human uterine myocytes"],"prefix":"10.1152","volume":"273","author":[{"given":"Raheela N.","family":"Khan","sequence":"first","affiliation":[{"name":"Department of Pharmacology, University of Cambridge, Cambridge CB2 1QJ; and"},{"name":"Department of Obstetrics and Gynaecology, University of Cambridge, The Rosie Maternity Hospital, Cambridge CB2 2SW, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephen K.","family":"Smith","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynaecology, University of Cambridge, The Rosie Maternity Hospital, Cambridge CB2 2SW, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. 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