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Baroreceptor control of pressure-flow relationships during hypoxemia
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 1, 1986
Summary
Hypoxemia impacts the carotid sinus reflex, affecting blood pressure and flow. Cardiovascular adjustments maintain blood flow during severe hypoxemia, even without peripheral chemoreceptors.
Area of Science:
- Cardiovascular Physiology
- Respiratory Physiology
Background:
- Peripheral chemoreceptors are crucial for detecting blood oxygen levels.
- The carotid sinus reflex regulates blood pressure via baroreceptors.
Purpose of the Study:
- To investigate the effects of hypoxemia on carotid sinus control of hemodynamics.
- To determine how the cardiovascular system responds to hypoxemia without peripheral chemoreceptors.
Main Methods:
- Studied anesthetized mongrel dogs with isolated and perfused carotid sinuses.
- Measured blood flow in aorta and regional arteries (celiac, mesenteric, renal, iliac).
- Applied graded hypoxemia and analyzed baroreceptor reflex responses.
Main Results:
- Carotid sinus reflex set-point pressure was maintained until severe hypoxemia.
- Maximal reflex gain occurred during mild hypoxemia; regional flows were unaffected.
- Hypoxemia potentiated reflex increases in aortic pressure and flow; regional flows increased.
Conclusions:
- The cardiovascular system maintains central and regional blood flow during hypoxemia, independent of peripheral chemoreceptors.
- Sympathetic stimulation during hypoxemia preserves blood flow at high pressures.
- Celiac blood flow regulation was notably independent of cardiac output changes.