Penitrem A

Penitrem A (tremortin) is a fungal neurotoxin found on ryegrass. It is produced by certain species of Aspergillus, Claviceps, and Penicillium. It inhibits potassium channels in smooth muscles. The maxi-channels targeted have their highest density in the cerebellar Purkinje cells.

It causes a stagger in horses and cattle.