Effects of aging on reflex autonomic nervous response induced by orthostatic maneuvers.
BACKGROUND
Baroreflex sensitivity (BRS), exercise pressor reflex (EPR), and aging influence the autonomic nervous response associated with orthostatic maneuvers. Standing significantly increases heart rate (HR), with an initial increase (1.deltaHR) due to EPR and a secondary, more gradual increase (2.deltaHR) due to BRS. HR then decreases (3.deltaHR), which is also attributable to BRS. Thus far, however, few data are available regarding the interdependence of these variables.


RESULTS
Ninety-five healthy volunteers (mean age 37 +/- 11 years, range 10-70 years; 50 women) underwent continuous noninvasive measurements of beat-to-beat blood pressure, HR, and spontaneous BRS in the supine (10 minutes) and upright (10 minutes) positions. After tilt, 1.deltaHR, 2.deltaHR, and 3.deltaHR were calculated from the HR recording. From the 1(st) to the 6(th) decade BRS, 2.deltaHR and 3.deltaHR decreased with normal aging ([BRS 11.88 +/- 7.97 ms/mmHg to 1.81 ms/mmHg, P = 0.006], 2.deltaHR [16.75 +/- 3.40 beats to 5.33 +/- 2.52 beats, P = 0.002], 3.deltaHR [52.25 +/- 5.91 beats to 11.33 +/- 4.04 beats, P < 0.001]). However, no such association was noted between 1.deltaHR and age (21.25 +/- 9.35 beats to 12.00 +/- 7.21 beats, ns). BRS while standing was correlated with 1.deltaHR (r = 0.432, P < 0.001).


CONCLUSIONS
EPR, in contrast to BRS, was not significantly influenced by normal aging. Furthermore, not only was BRS influenced by EPR, as is generally acknowledged, but EPR and BRS were interrelated. These observations offer new insights into the complex interactions of orthostasis-induced physiological autonomic reflexes associated with normal aging.
Barantke
Melanie
M
Medizinische Klinik II, Universitätsklinikum Schleswig-Holstein, Campus Lübeck, Lübeck, Germany.
Ortak
Jasmin
J
Lieb
Wolfgang
W
Wilke
Iris K
IK
Schunkert
Heribert
H
Bonnemeier
Hendrik
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001341:Autonomic Nervous System / Q000502:physiology*; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002648:Child; D015444:Exercise / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture