title: Carotid baroreflex control of arterial blood pressure at rest and during dynamic exercise in aging humans.
abstract: The arterial baroreflex is fundamental for evoking and maintaining appropriate cardiovascular adjustments to exercise. We sought to investigate how aging influences carotid baroreflex regulation of blood pressure (BP) during dynamic exercise. BP and heart rate (HR) were continuously recorded at rest and during leg cycling performed at 50% HR reserve in 15 young (22 ± 1 yr) and 11 older (61 ± 2 yr) healthy subjects. Five-second pulses of neck pressure and neck suction from +40 to -80 Torr were applied to determine the full carotid baroreflex stimulus response curve and examine baroreflex resetting during exercise. Although the maximal gain of the modeled stimulus response curve was similar in both groups at rest and during exercise, in older subjects the operating point (OP) was located further away from the centering point (CP) and toward the reflex threshold, both at rest (OP minus CP; -10 ± 3 older vs. 0 ± 2 young mmHg, P < 0.05) and during exercise (OP minus CP; -10 ± 2 older vs. 1 ± 3 young mmHg, P < 0.05). In agreement, older subjects demonstrated a reduced BP response to neck pressure (simulated carotid hypotension) and a greater BP response to neck suction (simulated carotid hypertension). In addition, the magnitude of the upward and rightward resetting of the carotid baroreflex-BP stimulus response curve with exercise was ∼40% greater in older individuals. These data indicate that despite a maintained maximal gain, the ability of the carotid baroreflex to defend against a hypotensive challenge is reduced, whereas responses to hypertensive stimuli are greater with advanced age, both at rest and during exercise.
authors.affiliation: School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: James P
authors.initials: JP
authors.lastname: Fisher
authors.forename: Areum
authors.initials: A
authors.lastname: Kim
authors.forename: Colin N
authors.initials: CN
authors.lastname: Young
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Fadel
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D017704:Baroreflex; D001794:Blood Pressure; D002346:Carotid Sinus / Q000294:innervation / Q000503:physiopathology*; D015444:Exercise; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007022:Hypotension / Q000503:physiopathology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017156:Photoplethysmography; D012146:Rest; D019722:Sphygmomanometers; D013997:Time Factors; D055815:Young Adult
references.citation: J Physiol. 1969 May;202(1):45P-46P
references.pmid: 5770914
references.citation: Cardiology. 1972;57(5):295-310
references.pmid: 4651782
references.citation: Ann N Y Acad Sci. 2004 Jun;1018:515-9
references.pmid: 15240409
references.citation: Med Sci Sports Exerc. 1982;14(5):377-81
references.pmid: 7154893
references.citation: Hypertension. 1998 Aug;32(2):298-304
references.pmid: 9719058
references.citation: J Physiol. 2005 Aug 15;567(Pt 1):311-21
references.pmid: 15946964
references.citation: J Physiol. 2005 Jul 15;566(Pt 2):599-611
references.pmid: 15890708
references.citation: Eur J Clin Invest. 2003 Jan;33(1):10-6
references.pmid: 12492447
references.citation: J Physiol. 1980 Jul;304:489-502
references.pmid: 7441548
references.citation: Circulation. 2002 Sep 10;106(11):1349-54
references.pmid: 12221051
references.citation: J Physiol. 2001 Jun 15;533(Pt 3):861-70
references.pmid: 11410641
references.citation: Am J Physiol Heart Circ Physiol. 2007 Jul;293(1):H777-83
references.pmid: 17449546
references.citation: J Physiol. 2007 Feb 15;579(Pt 1):227-36
references.pmid: 17138603
references.citation: Circulation. 1994 Apr;89(4):1648-55
references.pmid: 8149532
references.citation: J Physiol. 2001 Jun 15;533(Pt 3):871-80
references.pmid: 11410642
references.citation: Am J Physiol. 1993 Dec;265(6 Pt 2):H1928-38
references.pmid: 8285231
references.citation: Circulation. 2001 Nov 13;104(20):2424-9
references.pmid: 11705819
references.citation: Mayo Clin Proc. 1996 May;71(5):445-52
references.pmid: 8628023
references.citation: Circ Res. 1983 Mar;52(3):253-62
references.pmid: 6825218
references.citation: Mayo Clin Proc. 1984 Jul;59(7):467-75
references.pmid: 6539841
references.citation: Circulation. 2003 Feb 11;107(5):675-8
references.pmid: 12578866
references.citation: Exp Physiol. 2003 Nov;88(6):671-80
references.pmid: 14603365
references.citation: J Physiol. 2009 Nov 15;587(Pt 22):5427-39
references.pmid: 19805748
references.citation: Circulation. 2002 Mar 19;105(11):1329-35
references.pmid: 11901044
references.citation: Am J Physiol Heart Circ Physiol. 2001 Apr;280(4):H1454-63
references.pmid: 11247754
references.citation: Age Ageing. 2002 Sep;31(5):359-64
references.pmid: 12242198
references.citation: Blood Press Monit. 2004 Oct;9(5):269-75
references.pmid: 15472500
references.citation: Pflugers Arch. 1976 May 12;363(2):167-73
references.pmid: 945551
references.citation: Circulation. 1992 Aug;86(2):494-503
references.pmid: 1638717
references.citation: Acta Physiol Scand. 2004 Jul;181(3):289-95
references.pmid: 15196089
references.citation: J Physiol. 2004 Dec 15;561(Pt 3):893-901
references.pmid: 15498809
references.citation: J Appl Physiol (1985). 1996 Jun;80(6):1903-10
references.pmid: 8806893
references.citation: J Clin Invest. 1966 Jan;45(1):132-42
references.pmid: 5901176
references.citation: J Physiol. 2001 Nov 1;536(Pt 3):957-62
references.pmid: 11691887
references.citation: Exp Physiol. 2006 Jan;91(1):27-36
references.pmid: 16284242
references.citation: Am J Physiol. 1998 Nov;275(5):H1768-72
references.pmid: 9815084
references.citation: J Appl Physiol (1985). 1999 Jul;87(1):339-47
references.pmid: 10409593
references.citation: Am J Physiol. 1994 May;266(5 Pt 1):E717-24
references.pmid: 8203510
references.citation: Am J Physiol. 1992 Sep;263(3 Pt 2):H798-803
references.pmid: 1415605
references.citation: Auton Neurosci. 2001 Apr 12;88(1-2):74-85
references.pmid: 11474549
references.citation: J Auton Nerv Syst. 1996 Sep 12;60(3):209-12
references.pmid: 8912273
references.citation: Am J Physiol. 1997 Mar;272(3 Pt 2):H1157-64
references.pmid: 9087588
references.citation: J Physiol. 2007 Jul 1;582(Pt 1):63-71
references.pmid: 17463044
references.citation: J Physiol. 2002 Aug 15;543(Pt 1):349-64
references.pmid: 12181305
references.citation: Exp Physiol. 2006 Jan;91(1):37-49
references.pmid: 16210446
references.citation: J Physiol. 2007 May 15;581(Pt 1):405-18
references.pmid: 17317751
references.citation: J Physiol. 2009 May 1;587(Pt 9):2049-57
references.pmid: 19273575
references.citation: Am J Physiol Heart Circ Physiol. 2006 Oct;291(4):H2003-7
references.pmid: 16714364
references.citation: J Auton Nerv Syst. 1998 Nov 10;73(2-3):182-5
references.pmid: 9862394
references.citation: Circ Res. 1983 Jul;53(1):96-104
references.pmid: 6861300