THE ANTAGONISTIC ACTION OF EPHEDRINE (OR ADRENALINE) UPON THE CORONARY CONSTRICTION PRODUCED BY PITUITARY EXTRACT AND ITS EFFECT UPON BLOOD PRESSURE

¹ Department of Pharmacology, McGill University, Montreal, Canada

1. Experiments are presented which show that ephedrine or adrenaline leads to augmentation in the pressor responses to small doses of pituitary extract (posterior lobe) injected into the intact anesthetized animal.

2. Ephedrine or adrenaline (by continuous infusion) abolishes or diminishes the depressor action following the injection of large doses of pituitary extract in the intact anesthetized animal.

3. No augmentation of action is observed when the heart is replaced by Gibbs' artificial heart.

4. Ephedrine or adrenaline in suitable concentrations abolishes the diminution in cardiac output, following the injection of a large dose of pituitary extract (posterior lobe) in the heart-lung preparation. Large doses of ephedrine accentuate cardiac depression.

5. The cardiac rôle in these phenomena (1, 2) is demonstrated and the coronary dilating action of ephedrine and adrenaline which eliminates the constrictiong action of pituitary extract (posterior lobe) upon the coronary vessels is suggested as a plausible explanation.