{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,26]],"date-time":"2025-09-26T22:12:05Z","timestamp":1758924725529},"reference-count":0,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[1991,4,1]],"date-time":"1991-04-01T00:00:00Z","timestamp":670464000000},"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":[[1991,4]]},"abstract":"<jats:p>1. In the taenia isolated from the guinea\u2010pig caecum, changes in free intracellular magnesium concentration ([Mg2+]i) were measured based on the separation of the chemical shift of the alpha\u2010 and beta\u2010peaks of ATP obtained with nuclear magnetic resonance (NMR). 2. When external Mg2+ was increased from 1.2 to 12 and 40 mM, [Mg2+]i increased from 0.34 +\/\u2010 0.05 to 0.39 +\/\u2010 0.07 and 0.61 +\/\u2010 0.18 mM (n = 3), respectively, in 125\u2010150 min. In the absence of Ca2+, the increase was greater, i.e. [Mg2+]i reached 0.92 +\/\u2010 0.05 (n = 3) and 3.37 mM (n = 1), respectively. 3. In Ca(2+)\u2010 and Mg(2+)\u2010free solution, [Mg2+]i decreased to about 10 microM in 100 min. This decrease was not affected by substitution of Na+ with K+, but the recovery of [Mg2+]i on Mg2+ readmission was slower in the absence of Na+. This recovery was prevented by Ca2+ (2.4 mM), but Na+ readmission produced full recovery of [Mg2+]i in the presence of Ca2+. 4. When Na+ was substituted with K+ in the absence of Ca2+, [Mg2+]i increased from 0.38 +\/\u2010 0.01 mM to 0.56 +\/\u2010 0.04 mM (n = 4) in 100 min. Substitution of Na+ with N\u2010methyl\u2010D\u2010glucamine produced a much greater increase (to 2.1 mM in 100 min). Removal of the external K+ in the absence of Ca2+ also increased [Mg2+]i to 0.66 +\/\u2010 0.11 mM (n = 4) in 150 min, but no clear change was observed in the presence of Ca2+. Full recovery of [Mg2+]i could be produced in normal solution even when the intracellular phosphocreatine and ATP concentrations were 70\u201080% of the control. 5. It is concluded that in the smooth muscle of the guinea\u2010pig taenia caeci an Na(+)\u2010Mg2+ exchange process and possibly also an ATP\u2010driven Mg2+ pump are playing important roles in maintaining free [Mg2+]i at about 0.3 mM under the physiological condition. In addition to this, Ca2+ inhibits both Mg2+ efflux and influx, probably by reducing the membrane permeability to Mg2+ and by competing with Mg2+ in the Na(+)\u2010Mg2+ exchange of the plasma membrane.<\/jats:p>","DOI":"10.1113\/jphysiol.1991.sp018525","type":"journal-article","created":{"date-parts":[[2014,12,17]],"date-time":"2014-12-17T23:18:54Z","timestamp":1418858334000},"page":"559-572","source":"Crossref","is-referenced-by-count":21,"title":["Regulation of intracellular free magnesium concentration in the taenia of guinea\u2010pig caecum."],"prefix":"10.1113","volume":"435","author":[{"given":"S","family":"Nakayama","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T","family":"Tomita","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[1991,4]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1991.sp018525","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1991.sp018525","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,23]],"date-time":"2023-10-23T04:58:03Z","timestamp":1698037083000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1991.sp018525"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1991,4]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1991,4]]}},"alternative-id":["10.1113\/jphysiol.1991.sp018525"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1991.sp018525","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1991,4]]}}}