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Slow-wave flowmotion in rabbit skeletal muscle after acute fixed-volume hemorrhage
P Borgström1, J A Schmidt, S P Bruttig
1La Jolla Institute for Experimental Medicine, California 92037.
Abstract:
Laser Doppler flux (LDF) was used to detect flowmotion (regular cyclic alterations in red blood cell flux) in the left gastrocnemius muscle of 14 rabbits that were bled 30% of their blood volume and let to recover spontaneously for 30 min. Only rabbits that met stated inclusion criteria during control conditions were used in the study. During control conditions when femoral artery pressure averaged 68 mm Hg (range 60-80), no animal displayed regular flowmotion. After the end of the acute hemorrhage, arterial pressure was 35 mm Hg (20-51) and slow wave flowmotion appeared instantaneously in 13 of the 14 animals. The maximum relative amplitude of the induced flowmotion was 31% (7-100) and the frequency was 1.8 cycles per minute (cpm) (1.4-4.0). Flowmotion persisted throughout the 30 min observation period in 11 animals, during which time arterial pressure recovered to 46 mm Hg (42-50). Fast-wave flowmotion was not detected in the present study. These results suggest that slow-wave flowmotion as measured with LDF is not a phenomenon characteristic of normal regulation of blood flow in skeletal muscle. After a 30% fixed-volume hemorrhage, slow-wave flowmotion is induced as arterial pressure drops below a certain threshold.
Insights
Hemorrhage induces slow-wave flowmotion in rabbit skeletal muscle, detected by Laser Doppler flux (LDF). This regular alteration in red blood cell flux appears when arterial pressure drops below a specific threshold.
Area of Science:
- Physiology
- Hemodynamics
- Skeletal Muscle Biology
Background:
- Normal blood flow regulation in skeletal muscle is complex.
- Laser Doppler flux (LDF) is a technique used to measure microvascular blood flow.
- Flowmotion, or regular alterations in red blood cell flux, has been observed in various physiological states.
Purpose of the Study:
- To investigate the presence and characteristics of flowmotion in rabbit skeletal muscle.
- To determine if flowmotion is associated with normal blood flow regulation.
- To examine the effect of acute hemorrhage on flowmotion in skeletal muscle.
Main Methods:
- Laser Doppler flux (LDF) was employed to measure red blood cell flux in the left gastrocnemius muscle of rabbits.
- A 30% blood volume hemorrhage was induced, followed by a 30-minute spontaneous recovery period.
- Animals were monitored for the presence, amplitude, and frequency of flowmotion under control and post-hemorrhage conditions.
Main Results:
- No regular flowmotion was observed in rabbits under normal control conditions (mean arterial pressure 68 mm Hg).
- Following a 30% hemorrhage (arterial pressure dropped to 35 mm Hg), slow-wave flowmotion was instantaneously induced in 13 out of 14 rabbits.
- The induced slow-wave flowmotion exhibited a maximum relative amplitude of 31% and a frequency of 1.8 cycles per minute, persisting throughout the observation period.
Conclusions:
- Slow-wave flowmotion, as measured by LDF, is not a characteristic of normal skeletal muscle blood flow regulation.
- Acute hemorrhage and the resulting drop in arterial pressure below a certain threshold can induce slow-wave flowmotion.
- These findings suggest that slow-wave flowmotion may be a response to hypoperfusion rather than a normal regulatory mechanism.