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- Title
C056: Activation of sympathetic nervous activity by upright posture just after awakening.
- Authors
Yamasaki, F.; Sato, K.; Nishimori, Y.; Yamanaka, S.; Nakazawa, I.; Fujihara, T.; Chikamori, T.; Furuno, T.; Doi, Y.; Sugiura, T.
- Abstract
Although Morning blood pressure increase may be associated with autonomic nervous activity and movement after awake up, little is known about the effect of sympathetic nervous activity on blood pressure response. Consequently, we measured the autonomic nervous activity with serum norepinephrine level and heart rate/blood pressure fluctuation in 10 normal male volunteers (age 25-31 yrs) awaken up at 6:30 am. Arterial pressure and ECG were continuously recorded in supine and standing positions with controlled respiration (0.2 Hz) at 6:30 and 11:00 am. Low frequency (LF) components of the beat-to-beat fluctuations of RR interval and systolic arterial pressure (SAP) were estimated by autoregressive component power spectral analysis. Results showed that serum norepinephrine level (ng/ml) was lower at 6:30 than that at 11:00 (0.13 ± 0.05 vs. 0.21 ± 0.09, p < 0.05), which increased by head-up tilting at both of these points. However, increase in standing/supine ratio by head-up tilting (ΔHT) was higher at 6:30 than at 11:00 (2.94 ± 0.71 vs. 2.31 ± 0.81, p < 0.05). There was no significant difference in the LF power (normalized unit) of RR fluctuation between the two points, but the ΔHT was higher at 6:30 than at 11:00 (1.91 ± 0.68 vs. 1.49 ± 0.42, p < 0.05). Despite no significant difference in the LF power of SAP fluctuation between the two points, ΔHT tended to be higher at 6:30 than at 11:00 (2.22 ± 1.21 vs. 2.04 ± 1.10, ns). Thus, a greater activation of sympathetic nervous activity was observed by standing just after awakening compared to daytime, which may play an important roll in the morning surge of blood pressure.Am J Hypertens (2000) 13, 230A-230A; doi:S0895-7061(00)00906-7
- Publication
American Journal of Hypertension, 2000, Vol 13, p230A
- ISSN
0895-7061
- Publication type
Article
- DOI
10.1016/S0895-7061(00)00906-7