| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 School of Physical and Health Education and Department of Physiology, Queen's University, Kingston, Ontario, Canada
2 Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
* To whom correspondence should be addressed. E-mail: mt29{at}post.queensu.ca.
The purpose of this study was to test the hypothesis that sympathetic vasoconstriction is rapidly blunted at the onset of forearm exercise. 9 healthy subjects performed 5 min of dynamic forearm handgrip exercise during -60 mmHg lower body negative pressure (LBNP) vs. without (Control). Beat by beat forearm blood flow (FBF, Doppler ultrasound), arterial pressure (finger photoplethysmograph), and heart rate were collected. LBNP elevated resting heart rate by ~45%. Mean arterial pressure was not significantly changed (P=0.196), but diastolic pressure was elevated by ~10% and pulse pressure was reduced by ~20%. At rest, there was a 30% reduction in forearm vascular conductance (FVC) during LBNP (P=0.004). The initial rapid increase in FVC with exercise onset reached a plateau between 10-20 s of 126.6 ±4.1 ml/min/100mmHg in control vs. only 101.6 ±4.1 ml/min/100 mmHg in LBNP (main effect of condition, P = 0.003). This difference was quickly abolished during the second, slower phase of adaptation in forearm vascular tone to steady state. These data are consistent with a rapid onset of functional sympatholysis, in which local substances released with the onset of muscle contractions impair sympathetic neural vasoconstrictor effectiveness.
This article has been cited by other articles:
|
|
 |
|
  G. R. Chiappa, A. Borghi-Silva, L. F. Ferreira, C. Carrascosa, C. C. Oliveira, J. Maia, A. C. Gimenes, F. Queiroga Jr, D. Berton, E. M. V. Ferreira, et al. Kinetics of muscle deoxygenation are accelerated at the onset of heavy-intensity exercise in patients with COPD: relationship to central cardiovascular dynamics J Appl Physiol, May 1, 2008; 104(5): 1341 - 1350. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. E. Langen, K. D. Candido, M. King, G. Marra, and A. P. Winnie The Effect of Motor Activity on the Onset and Progression of Brachial Plexus Block with Bupivacaine: A Randomized Prospective Study in Patients Undergoing Arthroscopic Shoulder Surgery Anesth. Analg., February 1, 2008; 106(2): 659 - 663. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. F. Ferreira, S. Koga, and T. J. Barstow Dynamics of noninvasively estimated microvascular O2 extraction during ramp exercise J Appl Physiol, December 1, 2007; 103(6): 1999 - 2004. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. L. Walker, N. R. Saunders, D. Jensen, J. L. Kuk, S.-L. Wong, K. E. Pyke, E. M. Dwyer, and M. E. Tschakovsky Do vasoregulatory mechanisms in exercising human muscle compensate for changes in arterial perfusion pressure? Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H2928 - H2936. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Rogers, N. R. Saunders, K. E. Pyke, and M. E. Tschakovsky Rapid vasoregulatory mechanisms in exercising human skeletal muscle: dynamic response to repeated changes in contraction intensity Am J Physiol Heart Circ Physiol, September 1, 2006; 291(3): H1065 - H1073. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. J. Harper, L. F. Ferreira, B. J. Lutjemeier, D. K. Townsend, and T. J. Barstow Human femoral artery and estimated muscle capillary blood flow kinetics following the onset of exercise Exp Physiol, July 1, 2006; 91(4): 661 - 671. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. J. Behnke, D. J. Padilla, L. F. Ferreira, M. D. Delp, T. I. Musch, and D. C. Poole Effects of arterial hypotension on microvascular oxygen exchange in contracting skeletal muscle J Appl Physiol, March 1, 2006; 100(3): 1019 - 1026. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. R. Saunders, K. E. Pyke, and M. E. Tschakovsky Dynamic response characteristics of local muscle blood flow regulatory mechanisms in human forearm exercise J Appl Physiol, April 1, 2005; 98(4): 1286 - 1296. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. J. Green, W. Bilsborough, L. H. Naylor, C. Reed, J. Wright, G. O'Driscoll, and J. H. Walsh Comparison of forearm blood flow responses to incremental handgrip and cycle ergometer exercise: relative contribution of nitric oxide J. Physiol., January 15, 2005; 562(2): 617 - 628. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. D. Thomas and S. S. Segal Neural control of muscle blood flow during exercise J Appl Physiol, August 1, 2004; 97(2): 731 - 738. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
