Manoeuvres Affecting Sympathetic Outflow in Human Skin Nerves

Abstract Sympathetic activity was recorded from human skin nerves during the execution of a variety of different manoeuvres. The neural activity (composed of vasoconstrictor and sudomotor impulses) was regularly affected by emotional, thermal and respiratory stimuli. Mental stress, body cooling and increased respiratory movements all increased the sympathetic outflow, whereas the activity decreased during moderate body warming and when the. subject was calm and relaxed. Manoeuvres known to cause changes in baroreceptor activity usually did not affect the sympathetic outflow to the skin. When comparing neural and effector organ responses during the different manoeuvres the changes in sympathetic activity correlated well with changes in skin vascular resistance (either measured simultaneously or as reported in the literature). A comparison of the sympathetic responses recorded from human skin‐ and muscle nerves was also made. It was concluded that most manoeuvres had different effects in the two nerve types, thereby confirming earlier indirect evidence for selective regional control of the sympathetic outflow.