Trigeminal-baroreceptor reflex interactions modulate human cardiac vagal efferent activity

Area of Science:

• Cardiovascular Physiology
• Neuroscience
• Autonomic Nervous System Research

Background:

• Vagal cardiac inhibition is influenced by integrated neural inputs to vagal motonuclei.
• Understanding the interaction between sensory inputs is crucial for comprehending cardiac outflow regulation.

Purpose of the Study:

• To investigate the interaction between trigeminal cutaneous and carotid arterial baroreceptor inputs on human vagal cardiac outflow.
• To determine how face immersion and atropine affect these interactions.

Main Methods:

• Nine healthy young men maintained controlled breathing.
• Carotid baroreceptors were stimulated using neck suction.
• Participants underwent face immersion in cold water and received low-dose atropine sulphate.

Main Results:

• Face immersion increased blood pressure, heart period, baroreflex bradycardia, and respiratory sinus arrhythmia.
• Combined face immersion and atropine further augmented these cardiovascular responses.
• Trigeminal stimulation potentiated vagal responses to baroreceptor input.

Conclusions:

• Trigeminal cutaneous input enhances vagal cardiac outflow responses to arterial baroreceptor input.
• The interaction likely occurs downstream from the primary afferent fiber terminations.
• Respiration and low-dose atropine influence vagal motonuclei at a central processing level.