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Does capillary recruitment exist in young rabbit skeletal muscle?
H H Oude Vrielink1, D W Slaaf, G J Tangelder
1Department of Physiology, University of Limburg, Maastricht, The Netherlands.
International Journal of Microcirculation, Clinical and Experimental
|December 1, 1987
Summary
This study found no anatomical recruitment of arterioles or capillaries in rabbit tenuissimus muscle during vasodilation. All vessels perfused during vasodilation were already functional at rest.
Area of Science:
- Physiology
- Microcirculation
- Skeletal Muscle Biology
Background:
- Understanding microvascular responses is crucial for studying blood flow regulation.
- The concept of 'recruitment' in microcirculation suggests new vessels become perfused during increased demand.
Purpose of the Study:
- To investigate whether new terminal arterioles and capillaries are recruited in response to vasodilation in rabbit skeletal muscle.
- To determine if vasodilation leads to the perfusion of previously unperfused microvessels.
Main Methods:
- Intravital fluorescence microscopy was used to visualize and count perfused terminal arterioles and their branches in rabbit tenuissimus muscle.
- Bright field microscopy assessed the number of capillaries perfused from parent arterioles during rest and reactive hyperemia (vasodilation).
Main Results:
- All first-order side branches (terminal arterioles) perfused during vasodilation were also perfused at rest.
- Similarly, all capillaries perfused during vasodilation were already perfused under resting conditions.
- No new anatomical units of microcirculation were found to be recruited.
Conclusions:
- The study indicates that in this specific skeletal muscle preparation, vasodilation does not lead to the recruitment of new arterioles or capillaries in an anatomical sense.
- The findings suggest that increased blood flow during vasodilation is achieved by increased flow through existing perfused microvessels, rather than by opening new ones.