{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T16:49:03Z","timestamp":1762102143720},"reference-count":0,"publisher":"American Physiological Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Cell Physiology"],"published-print":{"date-parts":[[1989,8,1]]},"abstract":"<jats:p> There is disagreement regarding the existence of Ca2+-activated K+ channels in lymphocytes. Depolarization, hyperpolarization, or little change in membrane potential (Em) has been reported following elevation of free cytosolic Ca2+ concentration ([Ca2+]i). Patch-clamping studies have demonstrated inhibition of voltage-gated K+ channels, but Ca2+-activated K+ channels have not been detected. We used charybdotoxin (CTX), a potent inhibitor of Ca2+-activated K+ channels, to assess their presence in rat thymic lymphocytes. Fluorescent probes were used to measure Em and [Ca2+]i in cell suspensions treated with ionomycin. At basal [Ca2+]i, CTX had no effect on Em, suggesting that Ca2+-activated K+ channels do not contribute importantly to the resting potential. Elevation of [Ca2+]i in the submicromolar range induced a hyperpolarization that was dependent on the outward K+ gradient. The shape and duration of the Em change closely followed the elevation of [Ca2+]i. This hyperpolarization was inhibited by nanomolar concentrations of CTX. When [Ca2+]i approached or exceeded 1 microM, a biphasic Em change was recorded. A transient, CTX-sensitive hyperpolarization was followed by a sustained depolarization. The latter was greatly reduced when external Na+ was omitted. The data suggest that thymic lymphocytes possess Ca2+-sensitive K+ channels, which are activated by moderate increases in [Ca2+]i, resulting in hyperpolarization. At higher [Ca2+]i, the effect of K+ channels on Em is superseded by opening of nonselective cation channels, producing depolarization. Variations in the level of [Ca2+]i attained in earlier studies can explain existing discrepancies. <\/jats:p>","DOI":"10.1152\/ajpcell.1989.257.2.c197","type":"journal-article","created":{"date-parts":[[2017,12,24]],"date-time":"2017-12-24T15:28:58Z","timestamp":1514129338000},"page":"C197-C206","source":"Crossref","is-referenced-by-count":51,"title":["Ca2+ induces charybdotoxin-sensitive membrane potential changes in rat lymphocytes"],"prefix":"10.1152","volume":"257","author":[{"given":"S.","family":"Grinstein","sequence":"first","affiliation":[{"name":"Division of Cell Biology, Hospital for Sick Children, Toronto, Canada."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J. D.","family":"Smith","sequence":"additional","affiliation":[{"name":"Division of Cell Biology, Hospital for Sick Children, Toronto, Canada."}],"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.1989.257.2.C197","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,6,17]],"date-time":"2024-06-17T19:49:22Z","timestamp":1718653762000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.physiology.org\/doi\/10.1152\/ajpcell.1989.257.2.C197"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1989,8,1]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1989,8,1]]}},"alternative-id":["10.1152\/ajpcell.1989.257.2.C197"],"URL":"https:\/\/doi.org\/10.1152\/ajpcell.1989.257.2.c197","relation":{},"ISSN":["0363-6143","1522-1563"],"issn-type":[{"value":"0363-6143","type":"print"},{"value":"1522-1563","type":"electronic"}],"subject":[],"published":{"date-parts":[[1989,8,1]]}}}