{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:45:58Z","timestamp":1760147158527},"reference-count":0,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[1995,10,1]],"date-time":"1995-10-01T00:00:00Z","timestamp":812505600000},"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":[[1995,10]]},"abstract":"<jats:p>1. The effects of amiloride and ouabain on the regulation of the intracellular, free Mg2+ concentration ([Mg2+]i) were investigated in the taenia isolated from the guinea\u2010pig caecum, using nuclear magnetic resonance (NMR) techniques. 2. [Mg2+]i were mainly estimated from the separation of the alpha\u2010 and beta\u2010ATP peaks observed in 31P NMR spectra. In normal (physiological) and nominally Ca(2+)\u2010free solutions, [Mg2+]i was approximately 0.3\u20100.4 mM. Application of either amiloride or ouabain in Ca(2+)\u2010free solutions significantly increased [Mg2+]i, with only a small change in ATP content. Washout of the drugs reversed the changes in [Mg2+]i. 3. Changes in pHi were estimated from: (1) the chemical shift of phosphoethanolamine, and (2) solving two relational equations of pHi and [Mg2+]i obtained from the beta\u2010 and gamma\u2010ATP peaks. Both estimations revealed some intracellular alkalosis during application of these two drugs. After correction for pHi, a significant increase in [Mg2+]i was still obtained 150 min after application of either drug. 4. In the presence of amiloride, simultaneous removal of extracellular Mg2+ and Ca2+ significantly depleted intracellular Mg2+. This result suggests the presence of an amiloride\u2010insensitive (or less sensitive) pathway which passively transports Mg2+ across the plasma membrane. 5. The intracellular Rb+ concentration was monitored as an index of Na(+)\u2010K+ pump activity, using 87Rb NMR. In Ca(2+)\u2010free solutions containing 5 mM Rb+, the intracellular Rb+ concentration was hardly changed by amiloride, but was depleted by additional applications of ouabain. Wash\u2010out of ouabain restored the intracellular Rb+ in the presence of amiloride. 6. These results are consistent with the presence of Na(+)\u2010Mg2+ exchange as an effective Mg(2+)\u2010extruding mechanism in smooth muscle. Although many other factors may cause changes in [Mg2+]i, it seems likely that amiloride directly inhibits the Na(+)\u2010Mg2+ exchanger, whilst ouabain does so indirectly through reduction of the Na+ gradient across the plasma membrane.<\/jats:p>","DOI":"10.1113\/jphysiol.1995.sp020941","type":"journal-article","created":{"date-parts":[[2014,12,17]],"date-time":"2014-12-17T09:48:58Z","timestamp":1418809738000},"page":"1-12","source":"Crossref","is-referenced-by-count":12,"title":["Mechanisms of intracellular Mg2+ regulation affected by amiloride and ouabain in the guinea\u2010pig taenia caeci."],"prefix":"10.1113","volume":"488","author":[{"given":"S","family":"Nakayama","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"H","family":"Nomura","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[1995,10]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1995.sp020941","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1995.sp020941","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,10,26]],"date-time":"2023-10-26T04:03:16Z","timestamp":1698292996000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1995.sp020941"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1995,10]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1995,10]]}},"alternative-id":["10.1113\/jphysiol.1995.sp020941"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1995.sp020941","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1995,10]]}}}