Document Detail

Effect of nifedipine on choroidal blood flow regulation during isometric exercise.
MedLine Citation:
PMID:  22199246     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To determine whether nifedipine, an L-type calcium channel blocker, alters choroidal blood flow (ChBF) regulation during isometric exercise in healthy subjects.
METHODS: The study was carried out in a randomized, placebo-controlled, double-masked, two-way crossover design. Fifteen healthy male subjects were randomly assigned to receive either placebo or nifedipine on two different study days. Subfoveal ChBF was measured with laser Doppler flowmetry while the study participants performed isometric exercise (squatting). This was performed before drug administration and during infusion of nifedipine and placebo, respectively. Mean arterial pressure (MAP) and intraocular pressure (IOP) were measured noninvasively, and ocular perfusion pressure (OPP) was calculated as ⅔ MAP-IOP.
RESULTS: MAP and OPP increased significantly during all squatting periods (P < 0.01). The increase in ChBF was less pronounced than the increase in OPP during isometric exercise. Nifedipine did not alter the OPP increase in response to isometric exercise, but it significantly augmented the exercise-induced increase in ChBF (P < 0.001 vs. placebo). Although ChBF increased by a maximum of 14.2% ± 9.2% during the squatting period when placebo was administered, the maximum increase during administration of nifedipine was 23.2% ± 7.2%.
CONCLUSIONS: In conclusion, the data of the present study suggest that nifedipine augments the ChBF response to an experimental increase in OPP. In addition, it confirms that the choroidal vasculature has a significant regulatory capacity over wide ranges of OPPs during isometric exercise. ( number, NCT00280462.).
Doreen Schmidl; Ana Prinz; Julia Kolodjaschna; Elzbieta Polska; Alexandra Luksch; Gabriele Fuchsjager-Mayrl; Gerhard Garhofer; Leopold Schmetterer
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2012-01-25
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  53     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-27     Completed Date:  2012-04-02     Revised Date:  2013-01-09    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  374-8     Citation Subset:  IM    
Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
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MeSH Terms
Blood Flow Velocity
Blood Pressure / physiology
Body Constitution
Calcium Channel Blockers / administration & dosage*
Calcium Channels / physiology*
Choroid / blood supply*
Cross-Over Studies
Double-Blind Method
Exercise / physiology*
Infusions, Intravenous
Intraocular Pressure / physiology
Laser-Doppler Flowmetry
Nifedipine / administration & dosage*
Regional Blood Flow / physiology
Reg. No./Substance:
0/Calcium Channel Blockers; 0/Calcium Channels; 21829-25-4/Nifedipine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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