{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T16:39:54Z","timestamp":1781109594281,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"2","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1984,1]]},"abstract":"<jats:p>The relationship between the free cytoplasmic Ca2+ concentration, [Ca2+]i, and neurotransmitter release was investigated in guinea pig brain synaptosomes and the neurosecretory cell line PC12. Release was induced by alpha-latrotoxin, which acts in both Ca2+ -containing and Ca2+ -free incubation media, or by the classical depolarizing agents high K+ and veratridine, which require extracellular Ca2+. Two complementary approaches were used to reveal changes of [Ca2+]i: (i) direct measurement by a fluorescent Ca2+ indicator (quin2) and (ii) study of the Ca2+ -dependent phosphorylation of a protein, synapsin I, located at the cytoplasmic surface of synaptic vesicles. Depolarizing agents, when applied in Ca2+ -containing medium, induced the [Ca2+]i to increase promptly 3- to 6-fold, drastically increased synapsin I phosphorylation, and caused stimulation of transmitter release. With alpha-latrotoxin, the [Ca2+]i increase was delayed and occurred at a slower rate, the increase of synapsin I phosphorylation was less drastic, and the release response was much more pronounced. In Ca2+ -free medium, depolarizing agents released no transmitter and had no effect on [Ca2+]i or synapsin I phosphorylation, whereas with alpha-latrotoxin these processes were dissociated: considerable stimulation of the release without apparent change of [Ca2+]i and synapsin I phosphorylation. We conclude that the relationship between average [Ca2+]i and transmitter release is not straightforward and, in particular, that the release evoked by alpha-latrotoxin in Ca2+ -free medium is mediated by a factor(s) other than bulk redistribution of Ca2+ from intracellular stores.<\/jats:p>","DOI":"10.1073\/pnas.81.2.620","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T05:31:26Z","timestamp":1149053486000},"page":"620-624","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":90,"title":["Free cytoplasmic Ca2+ and neurotransmitter release: studies on PC12 cells and synaptosomes exposed to alpha-latrotoxin."],"prefix":"10.1073","volume":"81","author":[{"given":"J","family":"Meldolesi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"W B","family":"Huttner","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R Y","family":"Tsien","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"T","family":"Pozzan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1984,1]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.81.2.620","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T11:58:12Z","timestamp":1649851092000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.81.2.620"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1984,1]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1984,1]]}},"alternative-id":["10.1073\/pnas.81.2.620"],"URL":"https:\/\/doi.org\/10.1073\/pnas.81.2.620","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1984,1]]},"assertion":[{"value":"1984-01-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}