{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,22]],"date-time":"2026-02-22T23:39:12Z","timestamp":1771803552386,"version":"3.50.1"},"reference-count":0,"publisher":"American Physiological Society","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Cell Physiology"],"published-print":{"date-parts":[[1993,12,1]]},"abstract":"<jats:p> Smooth muscle cells in the intact guinea pig gallbladder had a resting membrane potential of about -45 mV and had spontaneous action potentials that consisted of a rapid depolarization, a transient repolarization, a plateau phase, and a complete repolarization. These action potentials lasted approximately 570 ms and occurred at a frequency of approximately 0.4 Hz. Action potentials were abolished by the dihydropyridine (DHP)-sensitive Ca2+ channel blocker nifedipine (1.0 microM) and were enhanced by the DHP-sensitive Ca2+ channel agonist BAY K 8644 (0.5 microM). The K+ channel blockers tetraethylammonium chloride (5.0 mM) and 4-aminopyridine (4-AP; 2.0 mM) prolonged the action potential, whereas charybdotoxin (100 nM), a blocker of calcium-activated potassium channels, had no effect. Whole cell currents were characterized in enzymatically isolated smooth muscle cells from the same preparation. 4-AP, a blocker of voltage-dependent K+ channels, suppressed 70% of the outward current at 0 mV. Charybdotoxin (100 nM) reduced an additional 15% of the current at 0 mV. Single calcium-activated potassium channels were identified. The potential for half-activation of these channels, at a cytosolic Ca2+ concentration of 100 nM, was 66.8 mV. A fivefold increase in cytosolic Ca2+ resulted in a shift of the activation curve by -53 mV. External tetraethylammonium chloride (200 microM) reduced the mean single channel current by 48% at 0 mV. The whole cell outward current was abolished by replacement of intracellular K+ for Cs+. Ca2+ currents were inhibited by nifedipine and were increased by BAY K 8644. We conclude that DHP-sensitive voltage-dependent Ca2+ channels are responsible for the depolarization of the action potentials and that the repolarization is due to primarily 4-AP-sensitive K+ current. <\/jats:p>","DOI":"10.1152\/ajpcell.1993.265.6.c1552","type":"journal-article","created":{"date-parts":[[2017,12,24]],"date-time":"2017-12-24T14:28:51Z","timestamp":1514125731000},"page":"C1552-C1561","source":"Crossref","is-referenced-by-count":48,"title":["Ionic basis of the action potential of guinea pig gallbladder smooth muscle cells"],"prefix":"10.1152","volume":"265","author":[{"given":"L.","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Anatomy, College of Medicine, University of Vermont,Burlington 05405."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A. D.","family":"Bonev","sequence":"additional","affiliation":[{"name":"Department of Anatomy, College of Medicine, University of Vermont,Burlington 05405."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M. T.","family":"Nelson","sequence":"additional","affiliation":[{"name":"Department of Anatomy, College of Medicine, University of Vermont,Burlington 05405."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"G. M.","family":"Mawe","sequence":"additional","affiliation":[{"name":"Department of Anatomy, College of Medicine, University of Vermont,Burlington 05405."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"24","container-title":["American Journal of Physiology-Cell Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.physiology.org\/doi\/pdf\/10.1152\/ajpcell.1993.265.6.C1552","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,6,17]],"date-time":"2024-06-17T19:40:58Z","timestamp":1718653258000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.physiology.org\/doi\/10.1152\/ajpcell.1993.265.6.C1552"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,12,1]]},"references-count":0,"journal-issue":{"issue":"6","published-print":{"date-parts":[[1993,12,1]]}},"alternative-id":["10.1152\/ajpcell.1993.265.6.C1552"],"URL":"https:\/\/doi.org\/10.1152\/ajpcell.1993.265.6.c1552","relation":{},"ISSN":["0363-6143","1522-1563"],"issn-type":[{"value":"0363-6143","type":"print"},{"value":"1522-1563","type":"electronic"}],"subject":[],"published":{"date-parts":[[1993,12,1]]}}}