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Pressor responses following a spontaneous burst of muscle sympathetic nerve activity: Influence of age and sex
Author(s) -
Vianna Lauro C,
Hart Emma C,
Fairfax Seth T,
Charkoudian Nisha,
Joyner Michael J,
Fadel Paul J
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.647.1
The sympathetic nervous system is critical to the beat‐to‐beat regulation of arterial blood pressure (BP). Although studies have examined age and sex related effects on BP control, the majority of studies have focused on time‐averaged responses without consideration for potential beat‐to‐beat alterations. In this regard, whether the ability of muscle sympathetic nerve activity (MSNA) to modulate BP on a beat‐to‐beat basis is affected by age or sex is unclear. Thus, we examined the magnitude of the rise in diastolic BP following a spontaneous burst of MSNA in 20 young (10 men) and 25 older (15 men) men and women. Arterial BP and MSNA (microneurography) were measured during a minimum of 5 min of supine rest (9.3±0.7 min). By signal averaging the beat‐to‐beat fluctuations in diastolic BP following each MSNA burst, a maximum rise in pressure was identified. The peak increase in diastolic BP to a burst of MSNA was reduced by ~42% in the older group (+2.9±0.2 older vs. +5.0±0.4 young mmHg; P<0.05). Although this attenuation appeared similar between sexes, the pressor responses of older women tended to be reduced in comparison to older men (+2.4±0.2 women vs. +3.3±0.3 men mmHg; P=0.083). The latency to the peak rise in BP was ~5 s, which was not altered by age or sex. These preliminary findings indicate that spontaneous bursts of MSNA consistently produce elevations in BP that are markedly reduced in older adults, regardless of sex. Supported by NIH HL‐093167 (PJF) and NIH HL‐83947 (MJJ)