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This Article Full Text Full Text (PDF) All Versions of this Article: 293/1/R185    most recent 00891.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Booth, L. C. Articles by Malpas, S. C. Search for Related Content PubMed PubMed Citation Articles by Booth, L. C. Articles by Malpas, S. C.

INNOVATIVE METHODOLOGY

NEUROHUMORAL CONTROL OF CARDIOVASCULAR FUNCTION

Cardiac-related rhythms in sympathetic nerve activity in preterm fetal sheep

Fetal Physiology and Neuroscience Group and Circulatory Control Laboratory, Department of Physiology, University of Auckland, Auckland, New Zealand

Submitted 20 December 2006 ; accepted in final form 20 March 2007

Extensive studies in the adult have demonstrated that the sympathetic nervous system plays a central role in cardiovascular control. The maturation of the sympathetic nervous system before birth is poorly understood. In the present study, we directly recorded renal sympathetic nerve activity (renal SNA) in five preterm fetal sheep (99 ± 1 days gestation; term is 147 days). Recordings were performed in utero using a telemetry-based technique to alleviate movement artifact without anesthesia or paralysis. The preterm fetuses exhibited a coordinated discharge pattern in renal SNA, indicating many individual neurons active at approximately the same time. This is consistent with that observed previously in adult animals, although the frequency of the bursts was relatively low (0.5 ± 0.1 Hz). The discharges in renal SNA were entrained to the cardiac cycle (average delay between diastolic pressure and maximum renal SNA 319 ± 1 ms). The entrainment of the sympathetic discharges to the cardiac cycle indicates phasic baroreceptor input and that the underlying circuits controlling SNA within the central nervous system are active in premature fetuses.

telemetry; renal sympathetic nerve activity

This article has been cited by other articles:

				L. C. Booth, S. C. Malpas, C. J. Barrett, S.-J. Guild, A. J. Gunn, and L. Bennet Is baroreflex control of sympathetic activity and heart rate active in the preterm fetal sheep? Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2009; 296(3): R603 - R609. [Abstract] [Full Text] [PDF]

				G. Wassink, L. Bennet, L. C. Booth, E. C. Jensen, B. Wibbens, J. M. Dean, and A. J. Gunn The ontogeny of hemodynamic responses to prolonged umbilical cord occlusion in fetal sheep J Appl Physiol, October 1, 2007; 103(4): 1311 - 1317. [Abstract] [Full Text] [PDF]