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Updated: Jul 31, 2026
09:34
In Vivo Canine Muscle Function Assay
Published on: April 5, 2011
Is active skeletal muscle functionally vasoconstricted during dynamic exercise in conscious dogs?
D S O'Leary1, E D Robinson, J L Butler
1Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
The American Journal of Physiology
|January 1, 1997
Summary
The sympathetic nervous system limits blood flow to active muscles during exercise. Blocking sympathetic signals with prazosin (PZ) increased hindlimb blood flow and vascular conductance, especially at higher exercise intensities.
Area of Science:
- Physiology
- Exercise Physiology
- Autonomic Nervous System
Background:
- Skeletal muscle blood flow increases significantly during dynamic exercise.
- The role of sympathetic nervous system restraint on this vasodilation is not fully understood.
Purpose of the Study:
- To investigate if sympathetic nervous system activity restrains hindlimb blood flow and vascular conductance during dynamic exercise in conscious dogs.
Main Methods:
- Conscious dogs were instrumented to measure hindlimb blood flow (TAQ) and mean arterial pressure (MAP).
- The alpha-adrenergic antagonist prazosin (PZ) was infused intra-arterially into the hindlimbs at rest and during graded treadmill exercise.
- Changes in TAQ and vascular conductance (TAC) were measured in response to PZ.
Main Results:
- Prazosin administration increased TAQ and TAC at rest and during exercise.
- The increase in TAQ and TAC with PZ was greater at higher exercise workloads.
- These increases were linearly related to control TAQ levels, indicating progressive sympathetic restraint.
Conclusions:
- The sympathetic nervous system progressively restrains vasodilation in active skeletal muscles during dynamic exercise.
- This sympathetic restraint limits skeletal muscle perfusion during exercise.
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