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Gender affects sympathetic and hemodynamic response to postural stress
J K Shoemaker1, C S Hogeman, M Khan
1Neurovascular Research Laboratory, School of Kinesiology, University of Western Ontario, London, Ontario, Canada, N6A 3K7. kshoemak@uwo.ca
American Journal of Physiology. Heart and Circulatory Physiology
|October 23, 2001
Summary
Men and women exhibit distinct autonomic nervous system responses to head-up tilt (HUT). Differences in muscle sympathetic nerve activity (MSNA) during HUT may explain poorer blood pressure control in women.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Research
- Human Physiology
Background:
- Autonomic nervous system regulation is crucial for maintaining blood pressure during postural changes.
- Previous research suggests potential gender differences in cardiovascular responses to stress.
- Understanding these differences is vital for addressing cardiovascular health disparities.
Purpose of the Study:
- To investigate gender-specific differences in sympathetic reflex responses to head-up tilt (HUT).
- To determine if variations in muscle sympathetic nerve activity (MSNA) contribute to reduced postural vasomotor control in females.
- To compare autonomic responses to both baroreflex-mediated (HUT) and non-baroreflex-mediated (cold pressor test) stressors.
Main Methods:
- Recruited 9 males and 8 females for a progressive head-up tilt (HUT) protocol.
- Measured muscle sympathetic nerve activity (MSNA) via microneurography.
- Monitored heart rate, stroke volume (SV), and blood pressure (BP) continuously during HUT and cold pressor test (CPT).
Main Results:
- Females exhibited a greater heart rate increase during HUT compared to males.
- Mean arterial pressure (MAP) increased less in females during HUT, despite similar increases in total peripheral resistance (TPR).
- Males showed a more pronounced neural response (MSNA) during the cold pressor test compared to females.
Conclusions:
- Significant gender-specific differences exist in autonomic responses to cardiovascular stress.
- Altered MSNA responses during HUT in females may contribute to impaired blood pressure regulation.
- These findings highlight the importance of considering gender in autonomic dysfunction research.