{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T08:22:17Z","timestamp":1772180537558,"version":"3.50.1"},"reference-count":69,"publisher":"Wiley","issue":"7","license":[{"start":{"date-parts":[[2021,5,20]],"date-time":"2021-05-20T00:00:00Z","timestamp":1621468800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["physoc.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Experimental Physiology"],"published-print":{"date-parts":[[2021,7]]},"abstract":"<jats:sec><jats:title>New Findings<\/jats:title><jats:p><jats:list list-type=\"bullet\">\n<jats:list-item><jats:p><jats:bold>What is the central question of this study?<\/jats:bold><\/jats:p>\n<jats:p>In the papillary muscle from type I diabetic rats, does diabetes\u2010associated altered ventricular function result from changes of acto\u2010myosin interactions and are these modifications attributable to a possible sarcomere rearrangement?<\/jats:p><\/jats:list-item>\n<jats:list-item><jats:p><jats:bold>What is the main finding and its importance?<\/jats:bold><\/jats:p>\n<jats:p>For the first time, we showed that type\u2010I diabetes altered sarcomeric ultrastructure, as seen by transmission electron microscopy, consistent with physiological parameters. The diabetic condition induced slower timing parameters, which is compatible with a diastolic dysfunction. At the sarcomeric level, augmented \u03b2\u2010myosin heavy chain content and increased sarcomere length and crossbridges' number preserve myocardial stroke and could concur to maintain the ejection fraction.<\/jats:p><\/jats:list-item>\n<\/jats:list><\/jats:p><\/jats:sec><jats:sec><jats:title>Abstract<\/jats:title><jats:p>We investigated whether diabetes\u2010associated altered ventricular function, in a type I diabetes animal model, results from a modification of acto\u2010myosin interactions, through the <jats:italic>in vitro<\/jats:italic> recording of left papillary muscle mechanical parameters and examination of sarcomere morphology by transmission electron microscopy (TEM). Experiments were performed on streptozotocin\u2010induced diabetic and age\u2010matched control female Wistar rats. Mechanical isometric and isotonic indexes and timing parameters were determined. Using Huxley's equations, we calculated mechanics, kinetics and energetics of myosin crossbridges. Sarcomere length and A\u2010band length were measured on TEM images. Type I and III collagen and \u03b2\u2010myosin heavy chain (MHC) expression were determined by immunoblotting. No variation in resting and developed tension or maximum extent of shortening was evident between groups, but diabetic rats showed lower maximum shortening velocity and prolonged timing parameters. Compared to controls, diabetics also displayed a higher number of crossbridges with lower unitary force. Moreover, no change in type I and III collagen was associated to diabetes, but pathological rats showed a two\u2010fold enhancement of \u03b2\u2010MHC content and longer sarcomeres and A\u2010band, detected by ultrastructural morphometry. Overall, these data address whether a preserved systolic function accompanied by an altered diastolic phase results from a recruitment of super\u2010relaxed myosin heads or the phosphorylation of the regulatory light chain site in myosin. Although the early signs of diabetic cardiomyopathy were well expressed, the striking finding of our study was that, in diabetics, sarcomere modification may be a possible compensatory mechanism that preserves systolic function.<\/jats:p><\/jats:sec>","DOI":"10.1113\/ep089000","type":"journal-article","created":{"date-parts":[[2021,5,12]],"date-time":"2021-05-12T01:20:35Z","timestamp":1620782435000},"page":"1572-1586","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["STZ\u2010diabetic rat heart maintains developed tension amplitude by increasing sarcomere length and crossbridge density"],"prefix":"10.1113","volume":"106","author":[{"given":"Raffaella","family":"Isola","sequence":"first","affiliation":[{"name":"Department of Biomedical Sciences Division of Cytomorphology University of Cagliari, Cittadella Universitaria di Monserrato  SP 8 Monserrato Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francesca","family":"Broccia","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences Division of Physiology University of Cagliari, Cittadella Universitaria di Monserrato  SP 8 Monserrato Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alberto","family":"Casti","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences Division of Cytomorphology University of Cagliari, Cittadella Universitaria di Monserrato  SP 8 Monserrato Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francesco","family":"Loy","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences Division of Cytomorphology University of Cagliari, Cittadella Universitaria di Monserrato  SP 8 Monserrato Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michela","family":"Isola","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences Division of Cytomorphology University of Cagliari, Cittadella Universitaria di Monserrato  SP 8 Monserrato Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6994-8105","authenticated-orcid":false,"given":"Romina","family":"Vargiu","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences Division of Physiology University of Cagliari, Cittadella Universitaria di Monserrato  SP 8 Monserrato Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2021,5,20]]},"reference":[{"key":"e_1_2_9_2_1","first-page":"173","article-title":"Myocardial adaptation to stress from the viewpoint of evolution and development","volume":"37","author":"Alpert N. 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