| Role of Endothelin-A receptors in optic nerve head red cell flux regulation during isometric exercise in healthy humans. | |
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MedLine Citation:
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PMID: 23103498 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Endothelin-1 (ET-1) is an important regulator of vascular tone in the eye. It appears to play a role in ocular disease, because of its strong vasoconstrictor action, its role in intraocular pressure homeostasis, and its neurotoxic potential. We have previously shown that ET-1 is involved in choroidal red cell flux (RCF) regulation during isometric exercise in healthy humans. In the present study we hypothesized that ET-1 also plays a role in optic nerve head (ONH) RCF regulation during isometric exercise. To test this hypothesis we performed a randomized, double-masked, placebo-controlled, two way crossover study in 15 healthy volunteers. Subjects were randomized to receive intravenous infusions of the specific ET(A) receptor antagonist BQ-123 and placebo on two different study days. During these infusion periods subjects performed squatting for 6 minutes to increase ocular perfusion pressure (OPP). ONH RCF was assessed with laser Doppler flowmetry and OPP was calculated from mean arterial pressure and intraocular pressure. BQ-123 did not change OPP or ONH RCF at baseline. The relative increase in OPP during isometric exercise was comparable between both groups (between 84% and 88 %, p = 0.76 between groups; p < 0.001 versus baseline). Isometric exercise increased ONH RCF during placebo and BQ-123, but the increase was more pronounced when the ET(A) receptor antagonist was administered (placebo: 27.3 ± 5.4 %; BQ-123: 39.2 ± 4.4 %; p = 0.007 between groups). The present data indicate that ET-1 regulates red cell flux in the ONH beyond the autoregulatory range. |
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Authors:
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Agnes Boltz; Doreen Schmidl; René M Werkmeister; Michael Lasta; Semira Kaya; Stefan Palkovits; Reinhard Told; Sophie Frantal; Gerhard Garhöfer; Leopold Schmetterer |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-10-26 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: - ISSN: 1522-1539 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2012 Oct |
Date Detail:
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Created Date: 2012-10-29 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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1Medical University of Vienna. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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