SCHEME 1.

(A) Schematic representation of the experimental protocol. Subjects consumed coffee or water 40 min before the start of the quantitative sudomotor axon reflex test (QSART). After QSART was ended, activated sweat gland density (ASGD) was measured. (B) Schematic from a single subject data sample showing axon reflex (AXR) (1) (shown with the red solid line), AXR (2) (shown with the blue dotted line) and direct activation responses (DIR, shown with the black solid line) by QSART. (C) Schematic of the time point of body temperature. Tympanic and local skin temperature of the chest, upper arm, thigh, and leg measurements were conducted continuously at 5 s intervals during the experiment (from immediately before intake coffee or water to 6 min after QSART). The temperature changes of the two groups were compared at three points: Rest, immediately before coffee or water intake; Pre, 40 min after coffee or water intake (immediately before QSART); Post, 6 min after QSART (immediately after all DIR and AXR (1), AXR (2) measurements have been completed). QSART, quantitative sudomotor axon reflex test; ACh, acetylcholine; AXR, axon reflex mediated (indirectly activated) sweating during (nicotinic receptor mediated sweating activity); AXR (1), AXR sweating during 5 min 10% ACh iontophoresis; AXR (2), AXR sweating during 5 min post-iontophoresis; DIR, directly activated sweating during (muscarinic receptor mediated sweating activity) 5 min post-iontophoresis.