{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T12:52:13Z","timestamp":1773665533278,"version":"3.50.1"},"reference-count":0,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[1975,6,1]],"date-time":"1975-06-01T00:00:00Z","timestamp":170812800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The Journal of Physiology"],"published-print":{"date-parts":[[1975,6]]},"abstract":"<jats:p>1. The influence of internal and external Na concentrations on Ca movements have been measured in pinch\u2010off presynaptic nerve terminals (synaptosomes). Ca uptake is enhanced when external Na (Nao) is replaced by Li, choline or dextrose, in Na\u2010loaded synaptosomes. Depletion of internal Na (Nai) abolishes the stimulatory effect of external Na removal. 2. Ca uptake from Na\u2010depleted media is proportional to [Na]i \u22122, and averages about 1\u20135 mumole Ca\/g synaptosome protein per minute when [Na]i is approximately 137 mM. This may correspond to a Ca influx of about 0\u20131 p\u2010mole\/cm\u20102 sec. 3. External Na is a competitive inhibitor of the Nai\u2010dependent Ca uptake. The interrelationship between [Na]o, [Ca]o and Ca uptake indicate that two external Na ions may compete with one Ca at each uptake site. 4. The distribution of particles with Nai\u2010dependent Ca uptake activity parallels the distribution of synaptosomes in the preparative sucrose gradient. Thus, this Ca uptake activity is probably a property of the pinched\u2010off nerve terminals per se, and not of the mitochondria which may contaminate the synaptosome fraction. 5. The Nai\u2010dependent Ca uptake mechanism requires an intact surface membrane, since synaptosomes subjected to osmotic lysis lose the ability to accumulate Ca by this route. 6. Ca efflux into Ca\u2010free media is largely dependent upon the presence of external Na. The curve relating Ca efflux to [Na]o is sigmoid, and suggests that more than one external Na ion (perhaps 2 or 3) is needed to activate the efflux of each Ca ion. 7. The net Ca gain exhibited by Na\u2010loaded synaptosomes incubated in Na\u2010depleted media can be accounted for by the increased Ca uptake and decreased Ca loss observed under these conditions. 8. Treatment of synaptosomes with cyanide or 2,4\u2010dinitrophenol decreases Ca uptake and enhances Ca efflux into Na\u2010containing media. This results in a net loss of Ca from the terminals, even in the presence of external Ca. 9. In contrast to the Ca efflux from synaptosomes, the Ca efflux from brain mitochondria is not dependent upon external Na, and is reduced by succinate, a substrate which is known to fuel mitochondrial respiration. 10. The temperature coefficient (Q10) of the Nai\u2010dependent Ca uptake is about 3. 11. The Nai\u2010dependent Ca uptake is reduced at low pH. The relationship between this Ca uptake and pH approximates a titration curve with a pKa of about 5\u20106. 12. The data indicate that Ca transport in rat brain presynaptic terminals may involve a carrier\u2010mediated Na\u2010Ca exchange mechanism, and that some of the energy required for Ca extrusion may come from the Na electrochemical gradient across the surface membranes.<\/jats:p>","DOI":"10.1113\/jphysiol.1975.sp010951","type":"journal-article","created":{"date-parts":[[2014,12,19]],"date-time":"2014-12-19T09:20:52Z","timestamp":1418980852000},"page":"657-686","source":"Crossref","is-referenced-by-count":138,"title":["The influence of sodium on calcium fluxes in pinched\u2010off nerve terminals in vitro."],"prefix":"10.1113","volume":"247","author":[{"given":"M P","family":"Blaustein","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C J","family":"Oborn","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[1975,6]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1975.sp010951","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1975.sp010951","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,6]],"date-time":"2023-11-06T02:31:18Z","timestamp":1699237878000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1975.sp010951"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1975,6]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1975,6]]}},"alternative-id":["10.1113\/jphysiol.1975.sp010951"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1975.sp010951","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1975,6]]}}}