Relationship between breathing and cardiovascular function at rest: sex-related differences.

Area of Science:

• Cardiovascular Physiology
• Autonomic Nervous System Regulation
• Sex Differences in Physiology

Background:

• Understanding sex-based differences in cardiovascular regulation is crucial for targeted health interventions.
• The interplay between respiratory patterns and autonomic control of circulation is not fully elucidated, particularly concerning sex-specific responses.

Purpose of the Study:

• To compare resting relationships between breathing rate, muscle sympathetic nerve activity, total peripheral resistance, and cardiac output in young men and women.
• To investigate potential sex differences in the neural and cardiovascular adjustments to breathing patterns.

Main Methods:

• Healthy young men (n=19) and women (n=17) underwent recordings of respiratory movements, muscle sympathetic nerve activity (microneurography), and cardiac output (acetylene uptake).
• Intra-arterial blood pressure, electrocardiogram, and calculated total peripheral resistance and stroke volume were analyzed over 4-minute epochs.

Main Results:

• While breathing rates and sympathetic activity were similar, women had lower blood pressure, cardiac output, and stroke volume than men.
• In men, breathing rate positively correlated with sympathetic activity, total peripheral resistance, and inversely with cardiac output and heart rate.
• No significant correlations between breathing rate and these cardiovascular variables were observed in women.

Conclusions:

• The findings suggest respiration influences tonic cardiovascular function in men via sympathetic activity and cardiac output modulation.
• The absence of these relationships in women indicates fundamental sex differences in blood pressure regulation and autonomic control.
• These sex-specific physiological responses underscore the need for gender-informed approaches in cardiovascular research and clinical practice.