Age-dependent vulnerability to carotid chemodenervation in piglets

Area of Science:

• Physiology
• Neonatal Research
• Respiratory Control

Background:

• Carotid chemoreceptors are crucial for regulating breathing and maintaining oxygen levels.
• The developmental trajectory of chemoreceptor function and its impact on respiratory stability in neonates is not fully understood.
• Understanding age-specific vulnerabilities is critical for preventing adverse respiratory events in vulnerable populations.

Purpose of the Study:

• To identify the specific age at which piglets exhibit the greatest vulnerability to the loss of carotid chemoreceptor function.
• To investigate the consequences of carotid body denervation on respiratory control and physiological stability in piglets.
• To determine if apnea and associated hypoxemia are state-dependent in the absence of functional carotid chemoreceptors.

Main Methods:

• Surgical removal of carotid bodies (carotid body-denervated, CBD) in piglets at four different age groups: 4-5, 9-10, 12-15, and 21-22 days.
• Control groups underwent sham surgery at corresponding ages.
• Post-surgery monitoring included continuous arterial oxygen saturation, electroencephalogram for sleep state recording, and assessment for apneic events during quiet and active sleep.

Main Results:

• Piglets denervated at 12-15 days (CBD15 group) exhibited numerous prolonged central apneic events during quiet sleep.
• These apneic events were associated with severe arterial oxygen desaturation, tachycardia, increased blood pressure, and electroencephalogram flattening.
• No such prolonged apneic events were observed in other CBD groups or intact control animals, indicating an age-specific vulnerability.

Conclusions:

• The absence of functional carotid chemoreceptors around 2 weeks of age renders piglets susceptible to life-threatening apneic events and severe hypoxemia.
• These severe respiratory events are specific to quiet sleep states in this age group.
• The findings highlight a critical developmental window of vulnerability in piglets related to carotid chemoreceptor function and respiratory control.