{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T05:08:28Z","timestamp":1791263308722,"version":"4.1.0"},"reference-count":37,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"9","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Circulation Research"],"published-print":{"date-parts":[[2009,10,23]]},"abstract":"\n \n \n Rationale<\/jats:underline>\n :\n <\/jats:italic>\n <\/jats:bold>\n Persistent atrial fibrillation (AF) has been associated with structural and electric remodeling and reduced contractile function.\n <\/jats:p>\n \n \n \n Objective<\/jats:underline>\n :\n <\/jats:italic>\n <\/jats:bold>\n To unravel mechanisms underlying reduced sarcoplasmic reticulum (SR) Ca\n 2+<\/jats:sup>\n release in persistent AF.\n <\/jats:p>\n \n \n \n Methods<\/jats:underline>\n :\n <\/jats:italic>\n <\/jats:bold>\n We studied cell shortening, membrane currents, and [Ca\n 2+<\/jats:sup>\n ]\n i<\/jats:sub>\n in right atrial myocytes isolated from sheep with persistent AF (duration 129\u00b139 days, N=16), compared to matched control animals (N=21). T-tubule density, ryanodine receptor (RyR) distribution, and local [Ca\n 2+<\/jats:sup>\n ]\n i<\/jats:sub>\n transients were examined in confocal imaging.\n <\/jats:p>\n \n \n \n Results<\/jats:underline>\n :\n <\/jats:italic>\n <\/jats:bold>\n Myocyte shortening and underlying [Ca\n 2+<\/jats:sup>\n ]\n i<\/jats:sub>\n transients were profoundly reduced in AF (by 54.8% and 62%,\n P<\/jats:italic>\n <0.01). This reduced cell shortening could be corrected by increasing [Ca\n 2+<\/jats:sup>\n ]\n i<\/jats:sub>\n . SR Ca\n 2+<\/jats:sup>\n content was not different. Calculated fractional SR Ca\n 2+<\/jats:sup>\n release was reduced in AF (by 20.6%,\n P<\/jats:italic>\n <0.05). Peak Ca\n 2+<\/jats:sup>\n current density was modestly decreased (by 23.9%,\n P<\/jats:italic>\n <0.01). T-tubules were present in the control atrial myocytes at low density and strongly reduced in AF (by 45%,\n P<\/jats:italic>\n <0.01), whereas the regular distribution of RyR was unchanged. Synchrony of SR Ca\n 2+<\/jats:sup>\n release in AF was significantly reduced with increased areas of delayed Ca\n 2+<\/jats:sup>\n release. Propagation between RyR was unaffected but Ca\n 2+<\/jats:sup>\n release at subsarcolemmal sites was reduced. Rate of Ca\n 2+<\/jats:sup>\n extrusion by Na\n +<\/jats:sup>\n \/Ca\n 2+<\/jats:sup>\n exchanger was increased.\n <\/jats:p>\n \n \n \n Conclusions<\/jats:underline>\n :\n <\/jats:italic>\n <\/jats:bold>\n In persistent AF, reduced SR Ca\n 2+<\/jats:sup>\n release despite preserved SR Ca\n 2+<\/jats:sup>\n content is a major factor in contractile dysfunction. Fewer Ca\n 2+<\/jats:sup>\n channel\u2013RyR couplings and reduced efficiency of the coupling at subsarcolemmal sites, possibly related to increased Na\n +<\/jats:sup>\n \/Ca\n 2+<\/jats:sup>\n exchanger, underlie the reduction in Ca\n 2+<\/jats:sup>\n release.\n <\/jats:p>","DOI":"10.1161\/circresaha.109.206276","type":"journal-article","created":{"date-parts":[[2009,9,18]],"date-time":"2009-09-18T05:34:37Z","timestamp":1253252077000},"page":"876-885","update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":166,"title":["Ultrastructural and Functional Remodeling of the Coupling Between Ca\n 2+<\/sup>\n Influx and Sarcoplasmic Reticulum Ca\n 2+<\/sup>\n Release in Right Atrial Myocytes From Experimental Persistent Atrial Fibrillation"],"prefix":"10.1161","volume":"105","author":[{"given":"Ilse","family":"Lenaerts","sequence":"first","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Virginie","family":"Bito","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Frank R.","family":"Heinzel","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ronald B.","family":"Driesen","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patricia","family":"Holemans","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan","family":"D'hooge","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hein","family":"Heidbu\u0308chel","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; and Department of Cardiology (F.R.H.), Medical University of Graz, Austria."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karin R.","family":"Sipido","sequence":"additional","affiliation":[{"name":"From the Divisions of Experimental Cardiology (I.L., V.B., R.B.D., P.H., K.R.S., R.W.) and Cardiac Imaging (J.D.), Department of Cardiovascular Medicine; Division of Clinical Cardiology (H.H., R.W.), UZ Gasthuisberg, University of Leuven, Belgium; 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