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Interaction of cardiac and muscle mechanical afferents on baroreflex control of the sinus node during dynamic exercise
Author(s) -
Vorluni L.,
Volianitis S.
Publication year - 2010
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/j.1600-0838.2009.00902.x
Subject(s) - supine position , baroreflex , baroreceptor , medicine , heart rate , heart rate variability , cardiology , blood pressure , anesthesia
The effects of cardiopulmonary baroreceptors and muscle mechanoreceptors stimulation on cardiac baroreflex sensitivity (BRS), and heart rate variability (HRV) were evaluated by measuring continuously and non‐invasively systolic blood pressure (SBP) and pulse interval (PI) during upright and supine passive cycling. BRS and HRV were evaluated with the cross‐correlation method ( x BRS) and in the frequency domain, respectively. At rest, the shift from upright to supine posture enhanced x BRS from 16.4±12.1 to 23.4±12.9 ms/mmHg, and the high frequency (HF, 0.15–0.4 Hz) power of HRV from 48.9±18.6 to 55.1±14.7 normalized units (NU), while it attenuated the low‐frequency (LF, 0.04–0.15 Hz) power from 51.1±18.6 to 44.9±14.7 NU ( P <0.05), respectively. During both upright and supine passive exercise, x BRS and the HF power were attenuated (10.0±8.0 and 12.5±9.0 ms/mmHg; 41.1±21.2 and 41.5±12.7 NU, respectively; P <0.05) and the LF power increased (58.8±21.2 and 58.5±12.7 NU, P <0.05), compared with rest. The effect of mechanoreflex activation overrides that of the cardiopulmonary baroreceptors loading resulting in decreased cardiac vagal outflow and reduced BRS during supine passive exercise.