On the influence of apomorphine on the toxicity of adrenalin and phenamine

Experiments on albino mice were used to determine the average lethal, doses of apomorphine, adrenalin, phenamine, and mixtures of apomorphine with adrenalin (1:3 and 3:1) and apomorphine with phenamine (1:3 and 3:1). The obtained values of average lethal doses for the mixtures were compared with those calculated according to these formulas: (1/LD_50M)=(P_a/LD_50a)+(P_b/LD_50b), where LD_50M is the average lethal dose of the mixture. LD_50a and LD_50b are the average lethal doses of its components and p_a and p_b are portions of the components in a mixture (p_a+p_b=1). This formula determines the relationship between the average lethal doses of a mixture and its components in case the latter's action is additive. It was shown that the effect of the combined action of apomorphine with adrenalin was considerably in excess of the additive effect whereas the effect of the combined action of apomorphine with phenamine was significantly less than the additive effect. These results were discussed from the viewpoint of the importance of pyrocatechol-O-methyltransferase in the inactivation of pyrocatecholamines.