| Extensible behavior of titin in the miniswine left ventricle. | |
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MedLine Citation:
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PMID: 20124120 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: The sarcomeric protein titin is a molecular spring responsible for passive tension and restoring forces of cardiomyocytes. Extension of titin as a function of sarcomere length (SL) has been studied in rodents, which predominantly express the smaller, stiffer N2B titin isoform. Large mammals coexpress roughly equal proportions of N2B and N2BA titin, the larger, more compliant isoform. We hypothesized that extension of titin in relation to SL differs in large mammals and that this difference is functionally important. METHODS AND RESULTS: We characterized the filling pressure-SL relation in diastolic-arrested miniswine left ventricles. SL was 2.15 to 2.25 mum at a filling pressure of approximately 0 mm Hg and reached a maximum of approximately 2.50 mum with overfilling. In the normal filling pressure range, SL ranged from approximately 2.32 to approximately 2.40 mum. We assessed titin extension as a function of SL using immunoelectron microscopy, which allowed delineation of the behavior of specific spring segments. The major isoform difference was that the N2B-Us segment extended approximately 4-fold more as a function of SL in N2B compared with N2BA titin. Using this segment, we estimated sarcomeric force development with a worm-like chain model and found that N2B develops markedly greater force than N2BA titin. The resulting force with coexpression of N2B and N2BA titin is intermediate. CONCLUSIONS: In light of murine studies showing that operating SLs are shorter than in miniswine, our results indicate that coexpression of the 2 titin isoforms in large mammals allows longer SLs without the development of excessive diastolic tension. |
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Authors:
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Martin M Lewinter; Joseph Popper; Mark McNabb; Lori Nyland; Stephen B Bell; Henk Granzier |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2010-02-01 |
Journal Detail:
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Title: Circulation Volume: 121 ISSN: 1524-4539 ISO Abbreviation: Circulation Publication Date: 2010 Feb |
Date Detail:
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Created Date: 2010-02-17 Completed Date: 2010-03-31 Revised Date: 2012-10-09 |
Medline Journal Info:
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Nlm Unique ID: 0147763 Medline TA: Circulation Country: United States |
Other Details:
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Languages: eng Pagination: 768-74 Citation Subset: AIM; IM |
Affiliation:
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Cardiology Unit, Fletcher Allen Health Care, 111 Colchester Ave, Burlington, VT 05401, USA. martin.lewinter@vtmednet.org |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Diastole / physiology Male Microscopy, Immunoelectron Models, Animal Muscle Proteins / physiology*, ultrastructure Myocardial Contraction / physiology Myocytes, Cardiac / physiology Protein Isoforms Protein Kinases / physiology*, ultrastructure Sarcomeres / physiology*, ultrastructure Swine Swine, Miniature Ventricular Function, Left / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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HL062881/HL/NHLBI NIH HHS; R01 HL061497/HL/NHLBI NIH HHS; R01 HL061497-05/HL/NHLBI NIH HHS; R01 HL062881/HL/NHLBI NIH HHS; R01 HL062881-09/HL/NHLBI NIH HHS; R01 HL61497/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Muscle Proteins; 0/Protein Isoforms; 0/connectin; EC 2.7.-/Protein Kinases |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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