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Microvascular flow routes in muscle controlled by vasoconstrictors
Lei Zhang1, John M B Newman, Stephen M Richards
1Biochemistry, Medical School, Private Bag 58, University of Tasmania, Hobart, TAS 7001, Australia.
Microvascular Research
|July 5, 2005
Summary
Vasoconstrictors alter rat hindlimb metabolism by redirecting blood flow. Angiotensin II increased capillary flow, while serotonin decreased it, rerouting flow to connective tissue vessels.
Area of Science:
- Physiology
- Vascular Biology
- Muscle Metabolism
Background:
- Vasoconstrictors' effects on muscle metabolism are debated.
- Previous studies suggested flow redistribution between nutritive and non-nutritive vessels.
Purpose of the Study:
- To identify perfused nutritive and non-nutritive vessels in rat hindlimb muscle.
- To determine how angiotensin II and serotonin affect intra-muscle blood flow distribution.
Main Methods:
- Perfusion fixation with glutaraldehyde and Griffonia simplicifolia lectin.
- Perfusion with rhodamine-dextran and formaldehyde fixation.
- Microscopic examination of muscle sections after perfusion with vehicle, angiotensin II, or serotonin.
Main Results:
- Angiotensin II increased perfused capillaries and reduced under-perfusion.
- Serotonin significantly decreased perfused capillaries.
- Serotonin promoted flow through larger, sparser connective tissue vessels.
Conclusions:
- Vasoconstrictors redistribute blood flow within muscles.
- Capillaries serve nutritive functions, while connective tissue vessels are non-nutritive.
- Altered metabolism by vasoconstrictors is linked to this flow redistribution.