Prostaglandin in the saliva of the cattle tick Boophilus microplus.

Previous studies of saliva from engorged female cattle ticks revealed a component which induced contration of some isolated smooth muscles. Fractionation and further characterisation have shown that this substance is of the "slow-reacting" type, but that it is neither a bradykinin nor slow-reacting substance of anaphylaxis. The substance is deactivated by incubation with 15-hydroxprostaglandin dehydrogenase and its pharmacological properties also support its classification as a prostaglandin. A second pharmacologically-active component has now been found in the saliva but has not yet been characterised.