EFFECT OF SCORPION TOXIN FROM TITYUS-SERRULATUS ON THE CONTRACTION OFTHE ISOLATED RAT UTERUS

Scorpion toxin T-1 from Tityus serrulatus was tested for its effects o n the isolated rat uterus preparation. T-1 (5 mu g/ml) caused a contra ction of the uterus, which was potentiated by neostigmine (1.64 x 10(- 6) M) and abolished by atropine (1.4 x 10(-7) M), After addition of ne ostigmine to the bath, we noted a higher amplitude of the toxin-induce d contractions, and the appearance of repetitive rhythmic contractions . The scorpion toxin-induced contraction was not prevented by previous addition to the bath of hexamethonium or bradykinin, 5-HT and angiote nsin II antagonists. The uterine contraction was prevented by previous addition to the bath of either tetrodotoxin (5 x 10(-8) M) or lidocai ne (4.2 x 10(-5) M). These data seem to indicate that scorpion toxin-i nduced rat uterus contractions are due to actions on post-ganglionic a utonomic nerve endings, with acetylcholine release and stimulation of muscarinic receptors.