HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J Appl Physiol 102: 735-739, 2007. First published October 26, 2006; doi:10.1152/japplphysiol.00618.2006
8750-7587/07 $8.00

This Article Free upon publication Full Text Free Full Text (PDF) Free All Versions of this Article: 102/2/735    most recent 00618.2006v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Momen, A. Articles by Sinoway, L. I. Search for Related Content PubMed PubMed Citation Articles by Momen, A. Articles by Sinoway, L. I.

Vasoconstriction seen in coronary bypass grafts during handgrip in humans

¹Penn State Heart and Vascular Institute, and ²Department of Health Evaluation Sciences, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania

Submitted 2 June 2006 ; accepted in final form 20 October 2006

In animal studies, sympathetically mediated coronary vasoconstriction has been demonstrated during exercise. Human studies examining coronary artery dynamics during exercise are technically difficult to perform. Recently, noninvasive transthoracic Duplex ultrasound studies demonstrated that 1) patients with left internal mammary artery (LIMA) grafts to the left anterior descending artery can be imaged and 2) the LIMA blood flow patterns are similar to those seen in normal coronary arteries. Accordingly, subjects with LIMA to the left anterior descending artery were studied during handgrip protocols as blood flow velocity in the LIMA was determined. Beat-by-beat analysis of changes in diastolic coronary blood flow velocity (CBV) was performed in six male clinically stable volunteers (60 ± 2 yr) during two handgrip protocols. Arterial blood pressure (BP) and heart rate (HR) were also measured, and an index of coronary vascular resistance (CVR) was calculated as diastolic BP/CBV. Fatiguing handgrip performed at [40% of maximal voluntary contraction (MVC)] followed by circulatory arrest did not evoke an increase in CVR (P = not significant). In protocol 2, short bouts of handgrip (15 s) led to increases in CVR (18 ± 3% at 50% MVC and 20 ± 8% at 70% MVC). BP was also increased during handgrip. Our results reveal that in conscious humans, coronary vasoconstriction occurs within 15 s of onset of static handgrip at intensities at or greater than 50% MVC. These responses are likely to be due to sympathetic vasoconstriction of the coronary circulation.

muscle reflexes; left internal mammary artery; autonomic nervous system

This article has been cited by other articles:

				D. S. O'Leary, J. A. Sala-Mercado, R. L. Hammond, E. J. Ansorge, J.-K. Kim, J. Rodriguez, D. Fano, and M. Ichinose Muscle metaboreflex-induced increases in cardiac sympathetic activity vasoconstrict the coronary vasculature J Appl Physiol, July 1, 2007; 103(1): 190 - 194. [Abstract] [Full Text] [PDF]