title: Neural control of blood pressure in women: differences according to age.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: LFE Research Group, Department of Health and Human Performance, Technical University of Madrid, Martín Fierro, 7, 28040, Madrid, Spain. anabelen.peinado@upm.es.
authors.forename: Ana B
authors.initials: AB
authors.lastname: Peinado
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Ronee E
authors.initials: RE
authors.lastname: Harvey
authors.affiliation: School of Physiology and Pharmacology, University of Bristol, Bristol, UK.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Hart
authors.affiliation: Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA.
authors.forename: Nisha
authors.initials: N
authors.lastname: Charkoudian
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Curry
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Wayne T
authors.initials: WT
authors.lastname: Nicholson
authors.affiliation: Institute of Neuroscience and Physiology, The Sahlgren Academy at Gothenburg University, Gotheborg, Sweden.
authors.forename: B Gunnar
authors.initials: BG
authors.lastname: Wallin
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Joyner
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN, USA.|Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Jill N
authors.initials: JN
authors.lastname: Barnes
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001337:Autonomic Agents / Q000494:pharmacology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005730:Ganglionic Blockers / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008593:Menopause / Q000502:physiology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D017698:Postmenopause / Q000502:physiology; D017697:Premenopause / Q000502:physiology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D014294:Trimethaphan / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D055815:Young Adult
chemical_list: D001337:Autonomic Agents; D005730:Ganglionic Blockers; D014665:Vasodilator Agents; D014294:Trimethaphan; C017774:trimethaphan camsylate
keywords: Aging; Baroreflex function; Menopause; Sympathetic nerve activity