Do peripheral and/or central chemoreflexes influence skin blood flow in humans?

Area of Science:

• Cardiovascular Physiology
• Respiratory Physiology
• Autonomic Nervous System Function

Background:

• Voluntary apnea activates central and peripheral chemoreceptors, increasing sympathetic nerve activity and causing limb vasoconstriction.
• The specific roles of peripheral and central chemoreceptors in mediating the cutaneous vasoconstrictor response during apnea are not fully understood.

Purpose of the Study:

• To investigate the contribution of peripheral and central chemoreceptors to the cutaneous vasoconstrictor response during voluntary apnea.
• To test hypotheses regarding the effects of hyperoxia, hypoxia, and hypercapnia on apnea-induced cutaneous vasoconstriction.

Main Methods:

• Healthy young men underwent three experiments involving voluntary apnea under different gas inhalation conditions (room air, 100% O2, 10% O2, or 7% CO2).
• Measurements included beat-by-beat blood pressure, heart rate, brachial blood flow velocity, and cutaneous vascular conductance.
• Changes in vascular conductance were compared between conditions to assess chemoreceptor influence.

Main Results:

• Hyperoxia (100% O2), which inhibits peripheral chemoreceptors, significantly attenuated the vasoconstrictor response in both muscle and skin during voluntary apnea compared to room air.
• Hypoxia (10% O2) and hypercapnia (7% CO2) did not significantly alter the cutaneous vasoconstrictor response to apnea.
• These findings suggest peripheral chemoreceptors play a key role in regulating skin blood flow during apnea.

Conclusions:

• Peripheral chemoreceptors are critical controllers of skin blood flow during voluntary apnea.
• Central chemoreceptors do not appear to significantly influence the cutaneous vasoconstrictor response to voluntary apnea.
• This study elucidates the chemoreceptor pathways involved in autonomic control of skin circulation during breath-hold maneuvers.