Once linaclotide reaches the gut, it binds to a receptor on the lining of the intestine and activates a cellular messenger called cyclic guanosine monophosphate.
During his presentation at Cambridge last week (see last post), Professor Paul Shellard mentioned that the new Planck data render many cyclic models, including the ekpyrotic universe, a lot less likely.
In 1998 Kandel's team injected aging mice with a failed antidepressant called Rolipram, which prevents the breakdown of cyclic-AMP by blocking an enzyme called phosphodiesterase-4.