Neural control of blood pressure in women: differences according to age
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The blood pressure “error signal” represents the difference between an individual’s mean diastolic blood pressure and the diastolic blood pressure at which 50% of cardiac cycles are associated with a muscle sympathetic nerve activity burst (the “T50”). In this study we evaluated whether T50 and the error signal related to the extent of change in blood pressure during autonomic blockade in young and older women, to study potential differences in sympathetic neural mechanisms regulating blood pressure before and after menopause.
We measured muscle sympathetic nerve activity and blood pressure in 12 premenopausal (25 ± 1 years) and 12 postmenopausal women (61 ± 2 years) before and during complete autonomic blockade with trimethaphan camsylate.
At baseline, young women had a negative error signal (−8 ± 1 versus 2 ± 1 mmHg, p < 0.001; respectively) and lower muscle sympathetic nerve activity (15 ± 1 versus 33 ± 3 bursts/min, p < 0.001; respectively) than older women. The change in diastolic blood pressure after autonomic blockade was associated with baseline T50 in older women (r = −0.725, p = 0.008) but not in young women (r = −0.337, p = 0.29). Women with the most negative error signal had the lowest muscle sympathetic nerve activity in both groups (young: r = 0.886, p < 0.001; older: r = 0.870, p < 0.001).
Our results suggest that there are differences in baroreflex control of muscle sympathetic nerve activity between young and older women, using the T50 and error signal analysis. This approach provides further information on autonomic control of blood pressure in women.
KeywordsAging Baroreflex function Menopause Sympathetic nerve activity
We thank Shelly Roberts, Sarah Wolhart, Luke Matzek, Alexander Allen, Casey Hines, Pamela Engrav, Nancy Meyer, and Christopher Johnson for their continued assistance throughout the project.
Compliance with ethical standards
This work was supported by National Institutes of Health grants RR024150 (Center for Translational Science Activities), AG038067 (Jill N. Barnes), HL083947 (B. Gunnar Wallin, Nisha Charkoudian, Michael J. Joyner), American Heart Association grant 2170087 (Emma C. Hart) and Mobility Grant Abroad “José Castillejo” for Young PhD CAS14/00239 (Ana B. Peinado).
Conflict of interest
No conflicts of interest, financial or otherwise, are declared by the authors.
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