{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T11:33:56Z","timestamp":1791891236647,"version":"4.3.4"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"12","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1990,6]]},"abstract":"<jats:p>Injection of rat brain mRNA into Xenopus oocytes has been shown to induce a calcium current (ICa) that is insensitive to dihydropyridine and omega-conotoxin. We examined the effect of funnel-web spider venom on two aspects of this expressed ICa: (i) the calcium-activated chloride current [ICl(Ca)] and (ii) the currents carried by barium ions through calcium channels (IBa). In the presence of 1.8 mM extracellular calcium, ICl(Ca) tail current became detectable between -30 and -40 mV from a holding potential of -80 mV and reached a maximal amplitude between 0 and +10 mV. Total spider venom partially (83%) and reversibly blocked the calcium-activated chloride current without changing its voltage sensitivity. A chromatographic toxin fraction from the venom also blocked this current (64%). The venom had a minimal effect on INa and IK. Direct investigation of inward current mediated by calcium channels was carried out in high-barium solution. IBa had a higher threshold of activation (-30 to -20 mV) and reached its maximal amplitude at about +20 mV. Total venom or a partly purified chromatographic toxic fraction blocked IBa partially and reversibly without changing its current-voltage characteristics. Furthermore, the extent of the total venom block depended on the concentration of extracellular barium. Only 35% of the IBa was blocked in 60 mM Ba2+, whereas the block increased to 65% and 71%, respectively, for 40 and 20 mM Ba2+. On the basis of these results, we propose that the calcium channels expressed from rat brain mRNA in Xenopus oocytes is similar to the recently discovered P-type channels.<\/jats:p>","DOI":"10.1073\/pnas.87.12.4538","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T07:22:02Z","timestamp":1149060122000},"page":"4538-4542","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":35,"title":["Funnel-web spider venom and a toxin fraction block calcium current expressed from rat brain mRNA in Xenopus oocytes."],"prefix":"10.1073","volume":"87","author":[{"given":"J W","family":"Lin","sequence":"first","affiliation":[{"name":"Department of Physiology and Biophysics, New York University Medical Center, NY 10016."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B","family":"Rudy","sequence":"additional","affiliation":[{"name":"Department of Physiology and Biophysics, New York University Medical Center, NY 10016."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R","family":"Llin\u00e1s","sequence":"additional","affiliation":[{"name":"Department of Physiology and Biophysics, New York University Medical Center, NY 10016."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1990,6]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.87.12.4538","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T12:49:33Z","timestamp":1649854173000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.87.12.4538"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1990,6]]},"references-count":0,"journal-issue":{"issue":"12","published-print":{"date-parts":[[1990,6]]}},"alternative-id":["10.1073\/pnas.87.12.4538"],"URL":"https:\/\/doi.org\/10.1073\/pnas.87.12.4538","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1990,6]]},"assertion":[{"value":"1990-06-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}