“Amplification of endogenous … injection of edrophonium , an acetylcholinesterase inhibitor which does not enter the central nervous system, into normal subjects-resulted in … the plasma concentrations of norepinephrine (153+/-15-234+/-29 pg/ml, P < 0.01) and epinephrine (16+/-3-34+/-5 pg/ml, … a single-isotope derivative method.”