| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 John B. Pierce Laboratory and 2 Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06519
Received 15 May 1996; accepted in final form 9 June 1997.
Fuglevand, Andrew J., and Steven S. Segal. Simulation
of motor unit recruitment and microvascular unit perfusion: spatial considerations. J. Appl. Physiol.
83(4): 1223-1234, 1997.
Muscle fiber activity is the principal
stimulus for increasing capillary perfusion during exercise. The
control elements of perfusion, i.e., microvascular units (MVUs), supply
clusters of muscle fibers, whereas the control elements of contraction,
i.e., motor units, are composed of fibers widely scattered throughout
muscle. The purpose of this study was to examine how the discordant
spatial domains of MVUs and motor units could influence the proportion of open capillaries (designated as perfusion) throughout a muscle cross
section. A computer model simulated the locations of perfused MVUs in
response to the activation of up to 100 motor units in a muscle with
40,000 fibers and a cross-sectional area of 100 mm2. The simulation increased
contraction intensity by progressive recruitment of motor units. For
each step of motor unit recruitment, the percentage of active fibers
and the number of perfused MVUs were determined for several conditions:
1) motor unit fibers widely dispersed and motor unit territories randomly located (which
approximates healthy human muscle),
2) regionalized motor unit
territories, 3) reversed recruitment
order of motor units, 4) densely
clustered motor unit fibers, and 5)
increased size but decreased number of motor units. The simulations
indicated that the widespread dispersion of motor unit fibers
facilitates complete capillary (MVU) perfusion of muscle at low levels
of activity. The efficacy by which muscle fiber activity induced
perfusion was reduced 7- to 14-fold under conditions that decreased the
dispersion of active fibers, increased the size of motor units, or
reversed the sequence of motor unit recruitment. Such conditions are
similar to those that arise in neuromuscular disorders, with aging, or
during electrical stimulation of muscle, respectively.
skeletal muscle; capillary; blood flow; muscle fiber distribution; regionalization; reinnervation; aging; electrical stimulation; perfusion heterogeneity
This article has been cited by other articles:
|
|
 |
|
  N. Lai, H. Zhou, G. M. Saidel, M. Wolf, K. McCully, L. B. Gladden, and M. E. Cabrera Modeling oxygenation in venous blood and skeletal muscle in response to exercise using near-infrared spectroscopy J Appl Physiol, June 1, 2009; 106(6): 1858 - 1874. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Van Teeffelen, H. Vink, B. T. Ameredes, A. M. Jones, S. Egginton, L. F. Ferreira, G. W. Schmid-Schoenbein, W. L. Murfee, S. S. Segal, K. Tyml, et al. J Appl Physiol, March 1, 2008; 104(3): 895 - 899. [Full Text] [PDF]
|
|
|
|
|
|
D. S. DeLorey, J. M. Kowalchuk, A. P. Heenan, G. R. duManoir, and D. H. Paterson Prior exercise speeds pulmonary O2 uptake kinetics by increases in both local muscle O2 availability and O2 utilization J Appl Physiol, September 1, 2007; 103(3): 771 - 778. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. C. Inyard, L. H. Clerk, M. A. Vincent, and E. J. Barrett Contraction Stimulates Nitric Oxide Independent Microvascular Recruitment and Increases Muscle Insulin Uptake Diabetes, September 1, 2007; 56(9): 2194 - 2200. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Mabanta, P. Valane, J. Borne, and M. D. Frame Initiation of remote microvascular preconditioning requires KATP channel activity Am J Physiol Heart Circ Physiol, January 1, 2006; 290(1): H264 - H271. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. L. Calbet, H.-C. Holmberg, H. Rosdahl, G. van Hall, M. Jensen-Urstad, and B. Saltin Why do arms extract less oxygen than legs during exercise? Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2005; 289(5): R1448 - R1458. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. Damon and J. C. Gore Physiological basis of muscle functional MRI: predictions using a computer model J Appl Physiol, January 1, 2005; 98(1): 264 - 273. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. M. Wigmore, B. M. Damon, D. M. Pober, and J. A. Kent-Braun MRI measures of perfusion-related changes in human skeletal muscle during progressive contractions J Appl Physiol, December 1, 2004; 97(6): 2385 - 2394. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. D. Delp and D. S. O'Leary Integrative control of the skeletal muscle microcirculation in the maintenance of arterial pressure during exercise J Appl Physiol, September 1, 2004; 97(3): 1112 - 1118. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. Tschakovsky and D. D. Sheriff Immediate exercise hyperemia: contributions of the muscle pump vs. rapid vasodilation J Appl Physiol, August 1, 2004; 97(2): 739 - 747. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Lo, A. J. Fuglevand, and T. W. Secomb Theoretical simulation of K+-based mechanisms for regulation of capillary perfusion in skeletal muscle Am J Physiol Heart Circ Physiol, August 1, 2004; 287(2): H833 - H840. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. L. Olive, J. M. Slade, C. S. Bickel, G. A. Dudley, and K. K. McCully Increasing blood flow before exercise in spinal cord-injured individuals does not alter muscle fatigue J Appl Physiol, February 1, 2004; 96(2): 477 - 482. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. Tschakovsky, A. M. Rogers, K. E. Pyke, N. R. Saunders, N. Glenn, S. J. Lee, T. Weissgerber, and E. M. Dwyer Immediate exercise hyperemia in humans is contraction intensity dependent: evidence for rapid vasodilation J Appl Physiol, February 1, 2004; 96(2): 639 - 644. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Lo, A. J. Fuglevand, and T. W. Secomb Oxygen delivery to skeletal muscle fibers: effects of microvascular unit structure and control mechanisms Am J Physiol Heart Circ Physiol, August 7, 2003; 285(3): H955 - H963. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Kindig, K. M. Kelley, R. A. Howlett, C. M. Stary, and M. C. Hogan Assessment of O2 uptake dynamics in isolated single skeletal myocytes J Appl Physiol, January 1, 2003; 94(1): 353 - 357. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. M. Sejersted and G. Sjogaard Dynamics and Consequences of Potassium Shifts in Skeletal Muscle and Heart During Exercise Physiol Rev, October 1, 2000; 80(4): 1411 - 1481. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. W G E Van Teeffelen and S. S Segal Effect of motor unit recruitment on functional vasodilatation in hamster retractor muscle J. Physiol., April 1, 2000; 524(1): 267 - 278. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. T. Hepple, M. C. Hogan, C. Stary, D. E. Bebout, O. Mathieu-Costello, and P. D. Wagner Structural basis of muscle O2 diffusing capacity: evidence from muscle function in situ J Appl Physiol, February 1, 2000; 88(2): 560 - 566. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. Prior, J. M. Foley, R. C. Jayaraman, and R. A. Meyer Pixel T2 distribution in functional magnetic resonance images of muscle J Appl Physiol, December 1, 1999; 87(6): 2107 - 2114. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
