J Korean Acad Nurs.  2011 Apr;41(2):191-196. 10.4040/jkan.2011.41.2.191.

Estrogen Attenuates the Pressor Response Mediated by the Group III Mechanoreflex

• Park SA
• Kim JK

• KMID: 1754160
• DOI: http://doi.org/10.4040/jkan.2011.41.2.191

Abstract

PURPOSE
We investigated the effects of group III mechanoreceptors to cardiovascular responses in both pre-menopausal woman and post-menopausal woman during passive ankle dorsiflexion (PAD).
METHODS
Twenty healthy volunteers (10 post-menopausal women and 10 pre-menopausal women) were recruited for this study. Stroke volume (SV), heart rate (HR), cardiac output (CO), and total vascular conductances (TVC) were measured continuously throughout the experiment. To stimulate the group III mechanoreceptors, PAD was performed for one minute.
RESULTS
The results showed that mean arterial pressure (MAP) mediated by the mechanoreflex activation was significantly increased in both groups. However, this pressor response was significantly higher in post-menopausal women. This reflex significantly increased both SV and CO in pre-menopausal women, while there were no differences in post-menopausal women. There was no difference in HR in either group. The mechanoreflex significantly decreased TVC in post-menopausal woman, while there was no difference in pre-menopausal woman.
CONCLUSION
The results indicate that the excessive pressor response mediated by the mechanoreflex occurs due to overactivity of group III mechanorecptors and the mechanism is produced mainly via peripheral vasoconstriction in post-menopausal women.

Keyword

Estrogen; Post-menopausal woman; Exercise pressor reflex; Group III mechanoreceptors; Cardiac output

MeSH Terms

Aged
Blood Pressure
Body Mass Index
Cardiac Output
Estrogens/*metabolism
Female
Heart Rate
Humans
Mechanoreceptors
Middle Aged
Postmenopause
Premenopause
Reflex, Stretch/*physiology
Stroke Volume

Figure

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  Figure 1 Experimental foot ankle dorsiflexion

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  Figure 2 Cardiovascular responses mediated by the mechanorefelx during foot ankle dorsiflexion. Values are mean±standard error. PMW=Premenopausal woman; PTW=Postmenopausal woman; Black Bar: baseline; Gray Bar: mechanoreflex activation. *Significantly different from baseline value, p<.05; #Significantly different from PMW, p<.05; MAP=mean arterial pressure; HR=heart rate; SV=stroke volume; CO cardiac output; TVC=total vascular conductances.

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