| INCREASED MYOCARDIAL STIFFNESS WITH MAINTENANCE OF LENGTH-DEPENDENT CALCIUM ACTIVATION BY FEMALE SEX HORMONES IN DIABETIC RAT. | |
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MedLine Citation:
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PMID: 21335468 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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A decrease in peak early diastolic filling velocity in postmenopausal women implies a sex hormone-related diastolic dysfunction. The regulatory effect of female sex hormones on cardiac distensibility therefore was evaluated in ovariectomized rat by determining the sarcomere length-passive tension relationship of ventricular skinned fiber preparations. Diabetes also was induced in the rat to assess the protective significance of female sex hormones on diastolic function. While ovariectomy had no effect on myocardial stiffness, collagen content or titin ratio, a significant increase in myocardial stiffness was observed in diabetic rat only when female sex hormones were intact. The increased stiffness in diabetic-sham rat was accompanied by an elevated collagen content due to increases in the levels of procollagen and Smad2. Surprisingly, the increased myocardial stiffness in diabetic-sham rat was accompanied by a shift towards a more compliant N2BA of cardiac titin isoforms. The pCa-active tension relationship was analyzed at fixed sarcomere lengths of 2.0 and 2.3 μm to determine the magnitude of changes in myofilament Ca(2+) sensitivity between the two sarcomere lengths. Interestingly, high expression of N2BA titin was associated with a suppressed magnitude of changes in myofilament Ca(2+) sensitivity only in diabetic-ovariectomized condition. Estrogen supplementation in diabetic-ovariectomized rats partially increased myocardial stiffness but completely reversed the change in myofilament Ca(2+) sensitivity. These results indicate a restrictive adaptation of myocardium governed by female sex hormones to maintain myofilament activity in compensation to the pathophysiological induction of cardiac dilatation by the diabetic condition. |
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Authors:
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Tepmanas Bupha-Intr; Ye Win Oo; Jonggonnee Wattanapermpool |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-2-18 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: - ISSN: 1522-1539 ISO Abbreviation: - Publication Date: 2011 Feb |
Date Detail:
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Created Date: 2011-2-21 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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1Mahidol University. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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