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Hypoventilation in ponies after carotid body denervation
Journal of Applied Physiology
|February 1, 1976
Summary
Carotid body denervation in ponies caused significant alveolar hypoventilation, demonstrating the carotid bodies' essential role in maintaining ventilation. Peripheral chemosensitivity was partially regained, with better pH compensation in blood than cerebrospinal fluid.
Area of Science:
- Physiology
- Respiratory System
- Neuroscience
Background:
- The carotid bodies are crucial peripheral chemoreceptors that regulate ventilation.
- Understanding their role is vital for respiratory control research.
Purpose of the Study:
- To investigate the long-term effects of carotid body denervation (CD) on ventilation and acid-base balance in ponies.
- To assess the recovery of peripheral chemosensitivity after CD.
Main Methods:
- Carotid body denervation (CD) or sham surgery (S) in ponies.
- Measurement of arterial blood gases and acid-base balance (blood and CSF) over 17 weeks.
- Assessment of resting ventilation and ventilatory responsiveness to hypoxia and NaCN infusion.
Main Results:
- CD ponies exhibited marked alveolar hypoventilation and hypercapnia (PaCO2 12-15 mmHg above control) at 1-2 weeks post-surgery.
- Hypoventilation and hypercapnia partially resolved, with PaCO2 stabilizing at ~6 mmHg above control by 4-17 weeks.
- CSF pH remained acidic in hypercapnic CD ponies, while arterial blood pH normalized.
- Ventilatory responsiveness changes paralleled resting ventilation.
Conclusions:
- Carotid bodies are essential for maintaining normal ventilation in ponies.
- Peripheral chemosensitivity is partially regained post-CD, though the locus is unestablished.
- pH compensation mechanisms function better in blood than in CSF during chronic hypercapnia.