Central volume expansion is pivotal for sustained decrease in heart rate during seated to supine posture change
| Autor: | Niels Juel Christensen, Peter Norsk, Anders Gabrielsen, Peter Bie, Bettina Pump, Tsutomu Kamo |
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| Rok vydání: | 2001 |
| Předmět: |
Adult
Male Suction (medicine) Baroreceptor Supine position Physiology Posture Hemodynamics Blood Pressure Norepinephrine Heart Rate Physical Stimulation Physiology (medical) Heart rate Hydrostatic Pressure Supine Position Humans Medicine Leg Blood Volume business.industry Baroreflex Adaptation Physiological Arginine Vasopressin Carotid Arteries Blood pressure medicine.anatomical_structure Anesthesia Circulatory system cardiovascular system Cardiology and Cardiovascular Medicine business Artery |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 281:H1274-H1279 |
| ISSN: | 1522-1539 0363-6135 |
| DOI: | 10.1152/ajpheart.2001.281.3.h1274 |
| Popis: | During prolonged, static carotid baroreceptor stimulation by neck suction (NS) in seated humans, heart rate (HR) decreases acutely and thereafter gradually increases. This increase has been explained by carotid baroreceptor adaptation and/or buffering by aortic reflexes. During a posture change from seated to supine (Sup) with similar carotid stimulation, however, the decrease in HR is sustained. To investigate whether this discrepancy is caused by changes in central blood volume, we compared ( n = 10 subjects) the effects of 10 min of seated NS (adjusted to simulate carotid stimulation of a posture change), a posture change from seated to Sup, and the same posture change with left atrial (LA) diameter maintained unchanged by lower body negative pressure (Sup + LBNP). During Sup, the prompt decreases in HR and mean arterial pressure (MAP) were sustained. HR decreased similarly within 30 s of NS (65 ± 2 to 59 ± 2 beats/min) and Sup + LBNP (65 ± 2 to 58 ± 2 beats/min) and thereafter gradually increased to values of seated. MAP decreased similarly within 5 min during Sup + LBNP and NS (by 7 ± 1 to 9 ± 1 mmHg) and thereafter tended to increase toward values of seated subjects. Arterial pulse pressure was increased the most by Sup, less so by Sup + LBNP, and was unchanged by NS. LA diameter was only increased by Sup. In conclusion, static carotid baroreceptor stimulation per se causes the acute ( |
| Databáze: | OpenAIRE |
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