Passive limb movement augments ventilatory response to CO2 via sciatic inputs in anesthetized rats

Area of Science:

• Physiology
• Respiratory control
• Neuroscience

Background:

• Passive limb movement (PLM) in humans causes a temporary increase in breathing (hyperpnea).
• The physiological mechanisms driving this response are not fully understood.
• Investigating PLM in animal models can elucidate these mechanisms.

Purpose of the Study:

• To determine if PLM in anesthetized rats elicits a hyperpnea.
• To investigate if PLM augments the ventilatory response to carbon dioxide (CO2).
• To ascertain the role of sciatic afferents in these responses.

Main Methods:

• Anesthetized rats underwent passive limb movement (PLM) and hypercapnia (5% CO2).
• Experiments were conducted before and after sciatic nerve transection.
• Electrical stimulation of the central sciatic nerve was also performed.

Main Results:

• Threshold PLM induced a phasic hyperpnea and augmented the ventilatory response to CO2.
• Both PLM-induced hyperpnea and the augmented CO2 response were significantly reduced after sciatic nerve transection.
• Electrical stimulation of the sciatic nerve mimicked these effects.

Conclusions:

• Sciatic afferents play a crucial role in mediating the ventilatory and hypercapnic responses to PLM.
• These findings suggest a neural pathway involving sciatic afferents that contributes to PLM-induced hyperpnea.