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This Article Full Text Full Text (PDF) All Versions of this Article: 290/2/H853    most recent 00184.2005v1 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 (3) Citing Articles via Google Scholar Google Scholar Articles by Murai, H. Articles by Kaneko, S. Search for Related Content PubMed PubMed Citation Articles by Murai, H. Articles by Kaneko, S.

The activity of a single muscle sympathetic vasoconstrictor nerve unit is affected by physiological stress in humans

Departments of ¹Internal Medicine and ²Health Science, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan

Submitted 24 February 2005 ; accepted in final form 22 August 2005

Recording of neural firing from single-unit muscle sympathetic nerve activity (MSNA) is a new strategy offering information about the frequency of pure sympathetic firing. However, it is uncertain whether and when single-unit MSNA would be more useful than multiunit MSNA for analysis of various physiological stresses in humans. In 15 healthy subjects, we measured single-unit and multiunit MSNA before and during handgrip exercise at 30% of maximum voluntary contraction for 3 min and during the Valsalva maneuver at 40 mmHg expiratory pressure for 15 s. Shapes of individual single-unit MSNA were proved to be consistent and suitable for further evaluation. Single-unit and multiunit MSNA exhibited similar responses during handgrip exercise. However, acceleration of neural firing determined from single-unit MSNA became steeper than multiunit MSNA during the Valsalva maneuver. During the Valsalva maneuver, unlike handgrip exercise, the distribution of multiunit burst between 0, 1, 2, 3, and 4 spikes was significantly shifted toward multiple spikes within a given burst (P < 0.05). These results indicated that evaluation of single-unit MSNA could provide more detailed and accurate information concerning the role and responses of neuronal discharges induced by various physiological stresses in humans, especially amid intense sympathetic activity.

microneurography; handgrip exercise; Valsalva maneuver

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