Abstract 2303: Effects of Aging and Baroreflexsensitivity on Exercise Pressor Reflex
Background - Baroreflexsensitivity (BRS), exercise pressor reflex (EPR) and aging have previously been demonstrated to influence autonomic nervous response after orthostatic manoeuvres. Standing significantly increases heart rate (HR), with an initial increase (1.Δ HR) due to EPR and a secondary, more gradual increase (2.Δ HR) due to BRS. Consecutively, HR decreases (3.Δ HR) which is also due to BRS. Thus far, however, almost no data is available on the interdependence of these variables.
Methods and Results - Ninety-five healthy volunteers (50 women and 45 men, mean age 37±11 years, range 10 –70 years) underwent continuous non-invasive measurement of beat-to-beat blood-pressure HR and spontaneous BRS (Finometer®, FMS) in a supine (10 minutes) and upright (10 minutes) position. After tilt 1.Δ HR, 2.Δ HR and 3.Δ HR were determined manually from the HR recording. From the 1st to the 6th decade BRS, 2.Δ HR, and 3.Δ HR decreased with normal aging [BRS (11.88±7.97 ms/mmHg to 1.81 ms/mmHg, p=0.006), 2.Δ HR (16.75±3.40 beats to 5.33±2.52 beats, p=0.002), 3.Δ HR (52.25±5.91 beats to 11.33±4.04 beats, p<0.001)]. However, no such association was noted between 1.Δ HR and age (21.25±9.35 beats to 12.00±7.21 beats, p=NS). BRS while standing was significantly correlated with 1.Δ HR (r=0.432, p<0.001).
Conclusions - The present study demonstrates that EPR, in contrast to BRS, is not significantly affected with normal aging. Furthermore, not only is BRS affected by EPR as is generally acknowledged, but EPR and BRS are also significantly interrelated. Thus, our findings offer new insights into the complex interactions of orthostasis induced physiological autonomic reflexes with normal aging.