Effect of pertussis toxin on the interaction of azepexole and halothane

The effect of pertussis toxin on the interaction of azepexole and halothane was determined on the guinea pig ileum. Both azepexole and halothane inhibited electrically induced contractions with IC50 values of 3.3 X 10(-6) M and 1.5 V/V%, respectively. The two drugs interacted synergistically at concentrations producing inhibition greater than 50%. Pretreatment with pertussis toxin reduced the potency of each agent individually and abolished the synergistic interaction. The results demonstrate that the effects of halothane and azepexole involve a pertussis-sensitive G protein, thus suggesting that the effects of volatile anesthetics are mediated in part by this group of membrane associated proteins.