Figure 1: A schematic diagram of the quantitative peripheral control sudomotor axon reflex test and central control sudomotor mechanism. The sympathetic nervous system acts in response to thermal stimuli (red solid-lined arrow) reaching the thermoregulation center through central transmission. In quantitative sudomotor axon reflex test, cholinergic stimulation, such as by drug stimulation with 10% acetylcholine and iontophoresis (2 mA for 5 min, shown with blue solid-lined arrow), binds directly to the muscarinic receptors (Rec) of the sweat glands and induces local sweating of DIR (direct activated sweating, black solid arrows). At the same time, the neurotransmitters bind to the nicotinic receptors (Rec) on the nerve endings distributed in the sweat glands. The signal generated by the receptors travels antidromically along the axon. It changes its direction toward the neighboring sweat glands (their ducts shown within the blue dotted circle) when it reaches the branching point. This is called the axon reflex (red dotted arrows).