Phenyl valerate and choline ester hydrolases in the platelets of human, hen, rat and mouse

1. The levels of phenyl valerate and choline ester hydrolases in the platelets of human and certain laboratory animals have been determined for comparison. 2. The activities of total phenyl valerate hydrolase (PVase), paraoxon insensitive phenyl valerate hydrolase (PI-PVase), paraoxon and mipafox resistant esterase (PMRE) and propionyl-cholinesterase (PChE) were maximal in hen followed by mouse, rat and human. 3. Neurotoxic esterase (NTE) and acetylcholinesterase (AChE) activities were concentrated in the platelets of hens followed by humans, rats and mice in order. 4. Maximum concentration of butyrylcholinesterase (BChE) was found in the platelets of hens followed by mice, humans and rats. 5. It is concluded that the normal levels of enzyme activities in the platelets of humans and various species of animals may help to evaluate the exposure risk to neurotoxic organophosphorous compounds.