One of the privileges of being in this business is your job description includes learning new things everyday.
To wit: Did you know the chemical that jolts you awake when you're scared is not adrenalin? The word is Adrenalin, with a capital "A." It is a trademarked word for epinephrine. http://en.wikipedia.org/wiki/Jokichi_Takamine">Jokichi Takamine created the trademark Adrenalin when he discovered epinephrine in 1900 or 1901 (there are minor discrepancies between Wikipedia and Webster's New World Dictionary, but they agree Adrenalin is capitalized). The Brits don't use the generic word epinephrine, they call it adrenaline — lowercase "a" and "e" on the end.
Many Americans, running the risk of being scolded by their American English teachers and the editors of the Associated Press, have adopted the British spelling. There's a self-help group here for stress junkies called Adrenaline Addicts Anonymous.
Does that explain why nobody has an epinephrine rush?