Actually, it's Vagusstoff (literally translated from German as "Vagus Substance") refers to the substance released by stimulation of the vagus nerve which causes a reduction in the heart rate. Discovered in 1921 by physiologist Otto Loewi , vagusstoff was the first confirmation of chemical synaptic transmission and the first neurotransmitter ever discovered. It was later confirmed to be acetylcholine , which was first identified by Sir Henry Hallett Dale in 1914. Because of his pioneering experiments, in 1936 Loewi was awarded the Nobel Prize in Physiology or Medicine , which he shared with Dale. Thanks to Dr. Henry Lester of Cal Tech for informing me of this interesting bit of neuro-history through his free online course entitled " Drugs and The Brain ". The information provided here is taken from the Wikipedia article on the topic.
