| Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium. | |
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MedLine Citation:
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PMID: 15923318 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Regional reductions in norepinephrine-tracer uptake are found in pigs with hibernating myocardium. Clinical studies would suggest that this is evidence for denervation; however, the functional responses to sympathetic stimulation have not been evaluated, and our previous studies with beta-adrenergic stimulation have not suggested denervation hypersensitivity. Therefore, pigs were chronically instrumented to produce hibernating myocardium characterized by chronic regional dysfunction and histological viability. Open-chest studies were performed to determine changes in regional function in response to both pre- and postjunctional stimulation. Regional segment shortening was reduced at rest in hibernating myocardium compared with controls (13 +/- 3% vs. 27 +/- 3%, P = 0.004). During stellate ganglion stimulation, regional function increased in both groups of animals (P = 0.008 vs. baseline), but the increase in hibernating myocardium was blunted compared with controls (Delta%, 3 +/- 2% vs. 8 +/- 3%, P = 0.04). Similar results occurred with intracoronary tyramine (10 mug/kg). Functional improvement during intravenous epinephrine infusion (0.35 mug.kg(-1).min(-1)) was also blunted in hibernating myocardium compared with controls (Delta%, 7 +/- 1% vs. 15 +/- 2%, P = 0.04). Even when the improvement in function was expressed relative to the reduced baseline, there was no evidence for catecholamine-mediated hypersensitivity in hibernating myocardium. We therefore conclude that functional responses to both pre- and postjunctional sympathetic stimulation are blunted in pigs with hibernating myocardium. In contrast to previous studies of infarcted, denervated, and acutely stunned myocardium, there is no catecholamine-induced hypersensitivity in hibernating myocardium. These data suggest a downregulation in functional responses to stimulation that would protect hibernating myocardium from demand-induced ischemia at the expense of contractile reserve during sympathetic stimulation. |
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Authors:
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Vladislav Ovchinnikov; Gen Suzuki; John M Canty; James A Fallavollita |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. Date: 2005-05-27 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: 289 ISSN: 0363-6135 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2005 Oct |
Date Detail:
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Created Date: 2005-09-15 Completed Date: 2005-10-24 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: United States |
Other Details:
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Languages: eng Pagination: H1719-28 Citation Subset: IM |
Affiliation:
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Center for Research in Cardiovascular Medicine, University at Buffalo, Buffalo, New York 14214, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Heart / innervation*, physiopathology* Myocardial Contraction / physiology Myocardial Stunning / physiopathology* Stellate Ganglion / drug effects, physiology Swine Sympathetic Nervous System / drug effects, physiology* Sympathomimetics / pharmacology Tachycardia / physiopathology Tyramine / pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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HL-55324/HL/NHLBI NIH HHS; HL-61610/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Sympathomimetics; 51-67-2/Tyramine |
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