| Aging decreases vasoconstrictor responses of coronary resistance arterioles through endothelium-dependent mechanisms. | |
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MedLine Citation:
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PMID: 15820206 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: Aging decreases coronary blood flow and maximal reserve capacity. Impaired blood flow capacity may be related to an increased vasoconstrictor capacity of coronary resistance vessels. This study tested the hypothesis that aging increases the vasoconstrictor responsiveness of coronary arterioles isolated from myocardium of young (4 months) and old (24 months) Fischer 344 rats. METHODS: Isolated coronary arterioles were cannulated and pressurized (60 cm H2O) via hydrostatic pressure reservoirs. RESULTS: Contrary to our hypothesis, aging decreased responsiveness of coronary arterioles to endothelin (ET, 1 x 10(-11)-3 x 10(-8) M), potassium chloride (KCl, 10-100 mM), and pressure-induced myogenic responses (0-140 cm H2O). Removal of the endothelium from coronary arterioles increased vasoconstriction to all agonists; however, age-related KCl vasoconstrictor response differences remained, suggesting that K+ channel activity and/or the relative contribution of specific K+ channels to maintenance of vascular smooth muscle membrane potential may change with age. Removal of the endothelium, in addition to increasing responsiveness, eliminated aging-induced differences in ET- and pressure-induced vasoconstriction. L-NAME (10(-5)) incubation resulted in a greater enhancement of spontaneous tone in arterioles from old rats compared to those of young rats. ETB (BQ-788, 3 x 10(-8)) receptor blockade eliminated the age-associated differences. CONCLUSION: Collectively, these data suggest an age-associated increase in endothelial modulation of coronary resistance vessel constriction. This enhanced endothelial attenuation of coronary arteriolar constriction appears to result from increased basal release of nitric oxide. These alterations of coronary vascular reactivity may contribute to age-induced redistribution of coronary blood flow and diminished cardiac function. |
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Authors:
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Robert D Shipley; Judy M Muller-Delp |
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Publication Detail:
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Type: Journal Article Date: 2004-12-08 |
Journal Detail:
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Title: Cardiovascular research Volume: 66 ISSN: 0008-6363 ISO Abbreviation: Cardiovasc. Res. Publication Date: 2005 May |
Date Detail:
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Created Date: 2005-04-11 Completed Date: 2005-09-01 Revised Date: 2005-11-17 |
Medline Journal Info:
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Nlm Unique ID: 0077427 Medline TA: Cardiovasc Res Country: Netherlands |
Other Details:
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Languages: eng Pagination: 374-83 Citation Subset: IM |
Affiliation:
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Department of Health and Kinesiology, Texas A & M University, College Station, Texas 77843, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Aging
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physiology* Animals Arterioles Blood Pressure / physiology Coronary Circulation / physiology* Endothelins / pharmacology Endothelium, Vascular / metabolism* Male NG-Nitroarginine Methyl Ester / pharmacology Nitric Oxide Synthase / antagonists & inhibitors Oligopeptides / pharmacology Piperidines / pharmacology Potassium Chloride / pharmacology Rats Rats, Inbred F344 Receptors, Endothelin / drug effects Vascular Resistance Vasoconstriction / physiology* Vasoconstrictor Agents / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/BQ 788; 0/Endothelins; 0/Oligopeptides; 0/Piperidines; 0/Receptors, Endothelin; 0/Vasoconstrictor Agents; 50903-99-6/NG-Nitroarginine Methyl Ester; 7447-40-7/Potassium Chloride; EC 1.14.13.39/Nitric Oxide Synthase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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