THE POTENTIATION AND PARALYSIS OF ADRENERGIC EFFECTS BY ERGOTOXINE AND OTHER SUBSTANCES

¹ From the Pharmacological Laboratory, College of the Pharmaceutical Society, London

1. Ergotoxine, yohimbine and F.933 were examined on the rabbit's ear, the frog's heart and the spinal cat for their interaction on adrenergic transmission.

2. In very low concentrations these substances are all capable of sensitizing the rabbit's ear to the action of adrenaline. No definite sensitization occurs in the other two preparations. In higher concentrations they antagonize the effect of adrenaline and adrenergic stimulation.

3. On the cat's nictitating membrane all three substances can abolish the effect of adrenaline without diminishing the effect of sympathetic stimulation. Indeed this latter effect may be increased.

4. It is pointed out that the action of ergotoxine towards adrenaline is fundamentally similar to that of cocaine.