{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T23:15:06Z","timestamp":1771629306462,"version":"3.50.1"},"reference-count":0,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[1973,7,1]],"date-time":"1973-07-01T00:00:00Z","timestamp":110332800000},"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":[[1973,7]]},"abstract":"<jats:p>1. The effects of Mn on the electrical and mechanical properties of frog muscle fibres have been studied.<\/jats:p><jats:p>2. In normal saline 10 or 20 m\n<jats:sc>M<\/jats:sc>\u2010Mn hyperpolarized the fibres and had no effect on the membrane resistance. In isotonic K<jats:sub>2<\/jats:sub>SO<jats:sub>4<\/jats:sub> saline, Mn increased the membrane resistance indicating that this agent reduced the conductance to K.<\/jats:p><jats:p>3. The action potential is prolonged by Mn while the overshoot amplitude is unaffected. The threshold of the action potential is shifted to more positive values of membrane potential.<\/jats:p><jats:p>4. The isometric twitch is reduced by 45% in 10 m\n<jats:sc>M<\/jats:sc>\u2010Mn; this effect is observed within 8 sec of the application.<\/jats:p><jats:p>5. Mn (10 m\n<jats:sc>M<\/jats:sc>) reduced K contractures induced by 40 or 75 m\n<jats:sc>M<\/jats:sc>\u2010K (constant [K].[Cl] product) and shifted to the right in a parallel manner the curve tension <jats:italic>vs.<\/jats:italic> log K concentration. The calculated mechanical threshold for K contractures was shifted from \u221248 to \u221233 mV.<\/jats:p><jats:p>6. Caffeine contractures (3\u20134 m\n<jats:sc>M<\/jats:sc>) and supramaximal K contractures (190 m\n<jats:sc>M<\/jats:sc>\u2010K) were unaffected by 10 m\n<jats:sc>M<\/jats:sc> indicating that contractile proteins and the ability of the sarcoplasmic reticulum to release Ca are not impaired.<\/jats:p><jats:p>7. It is concluded that Mn is mainly affecting the excitation\u2010contraction coupling by altering the mechanical threshold. Since Mn reduces the permeability to Ca in several excitable membranes, it is suggested that the mechanical threshold depends on the entry of Ca to the muscle.<\/jats:p>","DOI":"10.1113\/jphysiol.1973.sp010260","type":"journal-article","created":{"date-parts":[[2014,12,19]],"date-time":"2014-12-19T10:25:11Z","timestamp":1418984711000},"page":"129-147","source":"Crossref","is-referenced-by-count":24,"title":["Effects of manganese on the electrical and mechanical properties of frog skeletal muscle fibres"],"prefix":"10.1113","volume":"232","author":[{"given":"D. J.","family":"Chiarandini","sequence":"first","affiliation":[]},{"given":"E.","family":"Stefani","sequence":"additional","affiliation":[]}],"member":"311","published-online":{"date-parts":[[1973,7]]},"container-title":["The Journal of Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1113%2Fjphysiol.1973.sp010260","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/pdf\/10.1113\/jphysiol.1973.sp010260","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,11,8]],"date-time":"2023-11-08T13:08:50Z","timestamp":1699448930000},"score":1,"resource":{"primary":{"URL":"https:\/\/physoc.onlinelibrary.wiley.com\/doi\/10.1113\/jphysiol.1973.sp010260"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1973,7]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1973,7]]}},"alternative-id":["10.1113\/jphysiol.1973.sp010260"],"URL":"https:\/\/doi.org\/10.1113\/jphysiol.1973.sp010260","archive":["Portico"],"relation":{},"ISSN":["0022-3751","1469-7793"],"issn-type":[{"value":"0022-3751","type":"print"},{"value":"1469-7793","type":"electronic"}],"subject":[],"published":{"date-parts":[[1973,7]]}}}