Intracellular effector substance increasing or decreasing as a response
to the stimulation of a receptor by an agonist, considered as the 'first
messenger'.
Source:
PAC, 2004, 76, 1033
(Glossary of terms used in toxicokinetics (IUPAC Recommendations 2003))
on page 1070
Transformed and rewritten from PDF version (entry
http://www.iupac.org/goldbook/ST06842.pdf)
by: Miloslav Nic, Jiri Jirat, Bedrich Kosata, ICT Prague, Czech Republic
