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Slowing of carotid-cardiac baroreflex with standing and with isometric and dynamic muscle activity.
KTH, School of Technology and Health (STH), Environmental Physiology (Closed 20130701).ORCID iD: 0000-0001-6361-8965
1996 (English)In: American Journal of Physiology, ISSN 0002-9513, Vol. 271, no 4 Pt 2, H1363-1369 p.Article in journal (Refereed) Published
Abstract [en]

We hypothesized that the carotid-cardiac baroreflex becomes slowed in conditions with increased sympathetic activity. Changes in heart rate (HR) and blood pressure in response to 10-s trains of 50-mmHg pulses of neck suction (NS) were studied in six male subjects during supine rest, upright rest, isometric arm exercise at 30% of maximum voluntary contraction, and dynamic leg exercise at 100 W in the sitting position. Estimated mean carotid distending pressure increased by approximately 20 mmHg with 50-mmHg, QRS-triggered, pulsatile NS. Repeated NS sequences were performed in each condition. The amplitude of the bradycardic response was highly variable among the subjects and did not differ significantly between conditions, mean values ranging from 0.3 to 0.6 beats.min-1.mmHg-1. In supine rest, the full bradycardic response appeared within < 1 s, i.e., during or immediately after the R-R interval of the first NS pulse. In the other conditions it took significantly longer, 2-3 s or three to seven R-R intervals, for the full HR responses to develop. Our results support the notion that the carotid-cardiac baroreflex in humans becomes slowed under conditions of concurrent sympathetic stimulation.

Place, publisher, year, edition, pages
1996. Vol. 271, no 4 Pt 2, H1363-1369 p.
National Category
URN: urn:nbn:se:kth:diva-123256OAI: diva2:625583
NR 20140805Available from: 2013-06-05 Created: 2013-06-05 Last updated: 2014-01-20Bibliographically approved

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Sundblad, Patrik
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Environmental Physiology (Closed 20130701)
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