Article
Baroreflex Regulation of Sympathetic Vasomotor Tone in Women and in Men
Baroreflexregulation der Sympathischen Nervenaktivität bei Männern und Frauen
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Published: | August 10, 2005 |
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Background: Blood pressure tends to be lower in premenopausal women than in men of similar age. Previous studies suggested that the gender difference may be explained in part by differences in sympathetic nervous system regulation with a reduction in sympathetic activity in women.
Methods: We recruited 32 normal weight healthy subjects (17 men, 15 women). EKG for hear rate, brachial, and finger blood pressure (BP), and muscle sympathetic nerve activity (MSNA) were measured. Baroreflex heart rate and MSNA regulation were assessed using incremental phenylephrine and nitroprusside infusions.
Results: Baseline blood pressure was similar in men and in women. MSNA was 26±2.6 bursts / min in women and 18±1.8 bursts / min in men (p<0.05). We did not find a gender difference in phenylephrine or nitroprusside responsiveness. Baroreflex sensitivity for heart rate regulation was 17±3.2 msec/ mm Hg in women and 19±1.9 msec/ mm Hg in men (ns). Baroreflex sensitivity for MSNA regulation was -2.1±0.3 bursts/min/ mm Hg in women and -1.9±0.2 bursts/ min/ mm Hg in men (ns).
Conclusions: Our data is not consistent with a major difference in MSNA baroreflex regulation between young normal weight men and women. Furthermore, our study suggests that the previously described gender difference in MSNA may not be evident in all populations.