Effect of mental stress on skin sympathetic nerve activity: Are responses reproducible?

Abstract

The primary aim of this study was to quantify the effect of mental stress (MS) on skin sympathetic nerve activity (SSNA). There is limited quantitative data showing SSNA response to MS. Previous studies report divergent MSNA responses to MS. The second aim was to determine the reproducibility of SSNA to MS within a given day and 1 week later. Ten subjects (26±1 yr.) performed two bouts of mental arithmetic lasting 3 min. The bouts were separated by 45 min. One week later the subjects returned to repeat MS. All experiments were conducted in the supine posture during the morning hours. To maintain neutral skin temperature, each subject wore a custom suit (34–35°C). Skin blood flow and sweat rate were measured on the dorsal foot. MS elicited a marked increase in SSNA within the first 10 s (184±42%; P<0.01) in all subjects, which was less during the remaining period of MS but remained elevated (87±20; P<0.01). The pattern of responses to MS was unchanged during the second bout (10 s, 247±55%; 3 min avg., 133±29%) and during the retest 1 week later (10 s, 196±55%; 3 min avg., 117±36%). MS did not significantly affect cutaneous vascular conductance and sweat rate during any trial. In summary, MS elicits robust and reproducible increases in SSNA in humans. Thus unlike MS effect on MSNA, the pattern of SSNA is consistent during repeated trials on the same day and when performed 1 week later.Supported by NIH (HL109952)