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This Article Full Text Full Text (PDF) All Versions of this Article: 294/3/R681    most recent 00896.2007v1 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 ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Carter, J. R. Articles by Ray, C. A. PubMed PubMed Citation Articles by Carter, J. R. Articles by Ray, C. A.

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Physiological and Molecular Mechanisms Implicated in the Neural Control of Circulation

Sympathetic responses to vestibular activation in humans

¹Department of Exercise Science, Health and Physical Education, Michigan Technological University, Houghton, Michigan; and ²Heart and Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania

Activation of sympathetic neural traffic via the vestibular system is referred to as the vestibulosympathetic reflex. Investigations of the vestibulosympathetic reflex in humans have been limited to the past decade, and the importance of this reflex in arterial blood pressure regulation is still being determined. This review provides a summary of sympathetic neural responses to various techniques used to engage the vestibulosympathetic reflex. Studies suggest that activation of the semicircular canals using caloric stimulation and yaw rotation do not modulate muscle sympathetic nerve activity (MSNA) or skin sympathetic nerve activity (SSNA). In contrast, activation of the otolith organs appear to alter MSNA, but not SSNA. Specifically, head-down rotation and off-vertical axis rotation increase MSNA, while sinusoidal linear accelerations decrease MSNA. Galvanic stimulation, which results in a nonspecific activation of the vestibule, appears to increase MSNA if the mode of delivery is pulse trained. In conclusion, evidence strongly supports the existence of a vestibulosympathetic reflex in humans. Furthermore, attenuation of the vestibulosympathetic reflex is coupled with a drop in arterial blood pressure in the elderly, suggesting this reflex may be important in human blood pressure regulation.

sympathetic nerve activity; blood pressure; head-down rotation