{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,11]],"date-time":"2025-09-11T11:39:10Z","timestamp":1757590750050},"reference-count":0,"publisher":"Canadian Science Publishing","issue":"6","license":[{"start":{"date-parts":[[1981,6,1]],"date-time":"1981-06-01T00:00:00Z","timestamp":360201600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/www.nrcresearchpress.com\/page\/about\/CorporateTextAndDataMining"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Can. J. Physiol. Pharmacol."],"published-print":{"date-parts":[[1981,6,1]]},"abstract":"<jats:p> Early studies indicated that the BaCl<jats:sub>2<\/jats:sub>-induced contractions in the guinea pig ileum longitudinal muscle strip (GPI-LMS) were, in part, neuronal in origin. However, recent studies have suggested that BaCl<jats:sub>2<\/jats:sub>-induced contractions were produced by an action directly on the smooth muscle membrane. The purpose of this study was to investigate the mechanism of the BaCl<jats:sub>2<\/jats:sub> contractions in the GPI-LMS. Botulinum toxin (5\u2002\u00d7\u200210<jats:sup>5<\/jats:sup>\u2002MLD\/mL), which blocks the electrically induced release of acetylcholine (ACh), hemicholinium-3 (HC-3; 110\u2002\u03bcM), which blocks ACh synthesis, tetrodotoxin (TTX; 60 nM), which blocks Na<jats:sup>+<\/jats:sup> channels, black widow spider venom, which depletes the presynaptic neuron of neurotransmitter, and atropine (2.9\u2002\u03bcM), a potent muscarinic antagonist, had no effect on the BaCl<jats:sub>2<\/jats:sub> contractions. Desensitization of the GPI-LMS to substance P did not affect the BaCl<jats:sub>2<\/jats:sub> contraction. In Ca<jats:sup>2+<\/jats:sup>-free buffer the BaCl<jats:sub>2<\/jats:sub> dose\u2013response curve was shifted to the right. In Ca<jats:sup>2+<\/jats:sup>-free solution the time to 50% inhibition of the contractile response to ACh (73\u2002nM) and BaCl<jats:sub>2<\/jats:sub> (1.16\u2002mM) was 3.7 and 125\u2002min, respectively. The D 600 IC<jats:sub>50<\/jats:sub> for ACh and BaCl<jats:sub>2<\/jats:sub> contractions was 220 and 130\u2002nM, respectively. In Ca<jats:sup>2+<\/jats:sup>-free buffer either EGTA (0.53\u2002mM) or D 600 (1\u2002\u03bcM) were potent inhibitors of BaCl<jats:sub>2<\/jats:sub> contractions. These results suggest that in the GPI-LMS the BaCl<jats:sub>2<\/jats:sub> response is not mediated by a release of ACh (or substance P) because inhibitors of ACh release, synthesis, and receptors do not affect the responses. Also, the BaCl<jats:sub>2<\/jats:sub> contraction is not due to activation of Na<jats:sup>+<\/jats:sup> channels because TTX is without effect. The BaCl<jats:sub>2<\/jats:sub>-induced contraction appears to be mainly due to the movement of membrane bound Ca<jats:sup>2+<\/jats:sup> through D 600 sensitive Ca<jats:sup>2+<\/jats:sup> channels with extracellular Ca<jats:sup>2+<\/jats:sup> and possible passage of Ba<jats:sup>2+<\/jats:sup> ions intracellularly playing relatively minor roles. <\/jats:p>","DOI":"10.1139\/y81-081","type":"journal-article","created":{"date-parts":[[2011,4,23]],"date-time":"2011-04-23T20:48:04Z","timestamp":1303591684000},"page":"541-547","source":"Crossref","is-referenced-by-count":9,"title":["BaCl<sub>2<\/sub>-induced contractions in the guinea pig ileum longitudinal muscle: role of presynaptic release of neurotransmitters and Ca<sup>2+<\/sup> translocation in the postsynaptic membrane"],"prefix":"10.1139","volume":"59","author":[{"given":"John G.","family":"Clement","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"155","container-title":["Canadian Journal of Physiology and Pharmacology"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/www.nrcresearchpress.com\/doi\/pdf\/10.1139\/y81-081","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2020,1,5]],"date-time":"2020-01-05T16:23:46Z","timestamp":1578241426000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.nrcresearchpress.com\/doi\/10.1139\/y81-081"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1981,6,1]]},"references-count":0,"journal-issue":{"issue":"6","published-print":{"date-parts":[[1981,6,1]]}},"alternative-id":["10.1139\/y81-081"],"URL":"https:\/\/doi.org\/10.1139\/y81-081","relation":{},"ISSN":["0008-4212","1205-7541"],"issn-type":[{"value":"0008-4212","type":"print"},{"value":"1205-7541","type":"electronic"}],"subject":[],"published":{"date-parts":[[1981,6,1]]}}}