Document Detail


Quantitative analysis of exercise-induced enhancement of early- and late-systolic retrograde coronary blood flow.
MedLine Citation:
PMID:  20007853     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Coronary blood flow (CBF) is reduced and transiently reversed during systole via cardiac contraction. Cardiac contractility, coronary tone, and arterial pressure each influence systolic CBF (CBF(SYS)), particularly by modulating the retrograde component of CBF(SYS). The effect of concurrent changes in these factors on CBF(SYS) during dynamic exercise has not been examined. Using chronically instrumented swine, we hypothesized that dynamic exercise enhances retrograde CBF(SYS). Phasic CBF was examined at rest and during treadmill exercise [2-5 miles/h (mph)]. Absolute values of mean CBF over the cardiac cycle (CBF(CYCLE)) as well as mean CBF in diastole (CBF(DIAS)) and mean CBF(SYS) were increased by exercise, while relative CBF(DIAS) and CBF(SYS) expressed as percentage of mean CBF(CYCLE) were principally unchanged. Early retrograde CBF(SYS) was present at rest and increased in magnitude (-33 +/- 4 ml/min) and as a percent of CBF(CYCLE) (-0.6 +/- 0.1%) at 5 mph. This reversal was transient, comprising 3.7 +/- 0.3% of cardiac cycle duration at 5 mph. Our results also reveal that moderately intense exercise (>3 mph) induced a second CBF reversal in late systole before aortic valve closure. At 5 mph, late retrograde CBF(SYS) amounted to -53 +/- 11 ml/min (-3.1 +/- 0.7% of CBF(CYCLE)) while occupying 11.1 +/- 0.3% of cardiac cycle duration. Wave-intensity analysis revealed that the second flow reversal coincided with an enhanced aortic forward-going decompression wave (vs. rest). Therefore, our data demonstrate a predictable increase in early-systolic CBF reversal during exercise and additionally that exercise induces a late-systolic CBF reversal related to the hemodynamic effects of left ventricular relaxation that is not predictable using current models of phasic CBF.
Authors:
Shawn B Bender; Marc J van Houwelingen; Daphne Merkus; Dirk J Duncker; M Harold Laughlin
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-12-10
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  108     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-03-17     Completed Date:  2010-06-04     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  507-14     Citation Subset:  IM    
Affiliation:
Department of Biomedical Sciences, University of Missouri, Columbia, Missouri 65211, USA. benders@missouri.edu
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological
Animals
Blood Pressure
Coronary Circulation*
Exercise Test
Female
Models, Cardiovascular
Myocardial Contraction*
Physical Exertion*
Swine
Swine, Miniature
Systole
Time Factors
Ventricular Function, Left*
Ventricular Pressure
Grant Support
ID/Acronym/Agency:
AR-048523/AR/NIAMS NIH HHS; HL-52490/HL/NHLBI NIH HHS; RR-018276/RR/NCRR NIH HHS
Comments/Corrections
Comment In:
J Appl Physiol (1985). 2010 Mar;108(3):479-80   [PMID:  20075268 ]

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


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