Is baroreflex control of sympathetic activity and heart rate active in the preterm fetal sheep?

Show simple item record Booth, Lindsea en Malpas, Simon en Barrett, Carolyn en Guild, Sarah-Jane en Gunn, Alistair en Bennet, Laura en 2015-06-28T23:23:25Z en 2009-03 en
dc.identifier.citation American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 2009, 296 (3), pp. R603 - R609 en
dc.identifier.issn 0363-6119 en
dc.identifier.uri en
dc.description.abstract The arterial baroreflex is a fundamental reflex that buffers rapid changes in arterial blood pressure ( BP) via regulation of the heart rate and sympathetic nerve activity to the vasculature. In adults a sigmoidal relationship between BP and both heart rate and sympathetic nerve activity is well documented. Its role in blood pressure control before birth is unclear. Preterm babies have a high incidence of low BP, especially in the first few days of life, which could be related, in part, to immaturity of the baroreflex. In the present study, we investigated the baroreflex control of fetal heart rate and renal sympathetic nerve activity (RSNA) in preterm fetal sheep in utero ( 102 +/- 1 days of gestation; term 140 days). Phenylephrine was associated with a significant increase in BP from 38 +/- 2 to 58 +/- 3 mmHg and a decrease in heart rate (HR) from 177 +/- 4 to 116 +/- 8 beats per minute (bpm). Sodium nitroprusside was associated with a significant fall in BP from 38 +/- 2 to 26 +/- 1 mmHg and an increase in HR from 182 +/- 4 to 274 +/- 8 bpm. However, the time between the 50% changes in BP and HR was significantly greater after hypotension than hypertension ( 31 +/- 8 s vs. 14 +/- 5 s, P < 0.05). No significant changes in RSNA occurred with either stimulus. This suggests that there are different maturational tempos for the components of the central autonomic response to altered blood pressure. en
dc.description.uri en
dc.language English en
dc.publisher American Physiological Society en
dc.relation.ispartofseries American Journal of Physiology: Regulatory, Integrative and Comparative Physiology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from en
dc.rights.uri en
dc.subject telemetry en
dc.subject renal sympathetic nerve en
dc.subject NEWBORN LAMBS en
dc.subject RATE-VARIABILITY en
dc.subject VOLUME EXPANSION en
dc.subject NERVOUS-SYSTEM en
dc.subject ANGIOTENSIN-II en
dc.title Is baroreflex control of sympathetic activity and heart rate active in the preterm fetal sheep? en
dc.type Journal Article en
dc.identifier.doi 10.1152/ajpregu.90624.2008 en
pubs.issue 3 en
pubs.begin-page R603 en
pubs.volume 296 en
dc.rights.holder Copyright: American Physiological Society en
dc.identifier.pmid 19109368 en en
pubs.end-page R609 en
pubs.publication-status Published en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 84089 en Bioengineering Institute en ABI Associates en Medical and Health Sciences en Medical Sciences en Physiology Division en
dc.identifier.eissn 1522-1490 en
pubs.record-created-at-source-date 2010-09-01 en
pubs.dimensions-id 19109368 en

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