Prostaglandins. Von Euler reported that a lipid fraction of human seminal fluid had potent activities on smooth muscle, hence the name. Later, prostaglandins were found to be widely distributed in mammalian tissues and body fluids.

Noradrenaline shown to be the predominant transmitter of the effects of sympathetic nerve impulses.

In 1970 Euler shared the Nobel Prize in Physiology or Medicine with Katz and Axelrod "for their discoveries concerning the humoral transmitters in the nerve terminals and the mechanism for their storage, release and inactivation."