Quinacrine is a prostaglandin antagonist

Quinacrine, an anti-malarial with local anaesthetic properties, because of its fluorescence characteristics and its ability to combine with chromosomes and biological membranes has been widely used as a “probe”. The sites with which it combines in Torpedo marmorata electric organs have many of the characteristics of specific receptors. Using rat vascular and gastric smooth muscle we have shown that quinacrine can competitively antagonise the actions of prostaglandin E2. We suggest that the biological sites to which quinacrine binds can normally be occupied by prostaglandins.