Effect of the mycotoxins penitrem, paxilline and lolitrem B on the electromyographic activity of skeletal and gastrointestinal smooth muscle of sheep.

The electromyographic (EMG) activity of skeletal muscle was investigated as a method of recording the tremorgenic activity of the mycotoxins penitrem, paxilline and lolitrem B in sheep. EMG recordings were made concurrently from the abomasal antrum and duodenum to study the effects of these tremorgens on smooth muscle of the gut. Penitrem (2.2 to 7.5 micrograms kg-1) induced mild to moderate tremors within 15 to 20 minutes of injection which lasted for two to four hours. Paxilline (0.66 to 1.5 mg kg-1) induced mild to moderate tremors immediately which lasted for one to two hours. Lolitrem B (25 to 110 micrograms kg-1) had no effect at low doses, but at higher doses it produced tremors appearing over 20 to 30 minutes which persisted for more than 24 hours. The best measure of tremor indicated by skeletal muscle EMG was recorded from the shoulder area. The responses of smooth muscle of the antrum and duodenum to the tremorgens were variable. They included inhibitory effects on the antrum but no stimulation. The tremorgens had inhibitory effects on the duodenum on some occasions but on others, phase III migrating myoelectric complex-like activity was stimulated.