| Prolonged diastolic time fraction protects myocardial perfusion when coronary blood flow is reduced. | |
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MedLine Citation:
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PMID: 10393684 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Because coronary blood flow is impeded during systole, the duration of diastole is an important determinant of myocardial perfusion. The aim of this study was to show that coronary flow modulates the duration of diastole at constant heart rate. METHODS AND RESULTS: In anesthetized, open-chest dogs, diastolic time fraction (DTF) increased significantly when coronary flow was reduced by lowering perfusion pressure from 100 to 70, 55, and 40 mm Hg. On average, DTF increased from 0.47+/-0.04 to 0.55+/-0.03 after a pressure step from 100 to 40 mm Hg in control, from 0.42+/-0.04 to 0.47+/-0.04 after administration of adenosine, and from 0.46+/-0.07 to 0.55+/-0.06 after L-NMMA (mean+/-SD, 6 dogs for control and adenosine, 4 dogs for L-NMMA, all P<0.05). Flow normalized to its value at full dilation and pressure of 90 mm Hg (375+/-25 mL/min) increased during the period of reduced pressure at 40 mm Hg; control, from 0.005+/-63 (2 seconds after pressure step) to 0.09+/-0.06 (15 seconds after pressure step); with adenosine, from 0.19+/-0.06 to 0. 22+/-0.06; and with L-NMMA, from 0.013+/-0.007 to 0.12+/-0.02 (all P<0.05). The increase in DTF at low pressure may be explained by a decrease in interstitial volume at low pressure, which either decreases the preload of the myocytes or reduces the buffer capacity for ions determining repolarization, thereby causing an earlier onset of relaxation. CONCLUSIONS: Because the largest increase in DTF occurs at pressures below the autoregulatory range when blood flow to the subendocardium is closely related to DTF, modulation of DTF by coronary blood flow can provide an important regulatory mechanism to match supply and demand of the myocardium when vasodilatory reserve is exhausted. |
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Authors:
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D Merkus; F Kajiya; H Vink; I Vergroesen; J Dankelman; M Goto; J A Spaan |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Circulation Volume: 100 ISSN: 1524-4539 ISO Abbreviation: Circulation Publication Date: 1999 Jul |
Date Detail:
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Created Date: 1999-07-16 Completed Date: 1999-07-16 Revised Date: 2006-11-15 |
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: 75-81 Citation Subset: AIM; IM |
Affiliation:
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Department of Medical Physics, Cardiovascular Research Institute Amsterdam, Academic Medical Center, University of Amsterdam, The Netherlands. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine
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pharmacology Animals Blood Pressure Cardiac Pacing, Artificial Cardiovascular Agents / pharmacology Coronary Circulation / physiology* Diastole / physiology* Dogs Enzyme Inhibitors / pharmacology Heart / drug effects, physiopathology Muscle Relaxation Myocardial Ischemia / physiopathology* Myocardium / pathology Nitric Oxide Synthase / antagonists & inhibitors Nitric Oxide Synthase Type III Perfusion Time Factors Vascular Resistance omega-N-Methylarginine / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Cardiovascular Agents; 0/Enzyme Inhibitors; 17035-90-4/omega-N-Methylarginine; 58-61-7/Adenosine; EC 1.14.13.39/Nitric Oxide Synthase; EC 1.14.13.39/Nitric Oxide Synthase Type III |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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