THE ANTIDIURETIC ACTION OF MORPHINE, AND ITS MECHANISM

¹ From the Department of Pharmacology, New York University College of Medicine

1. When normal dogs in the postabsorptive state and in water equilibrium are given water, either by stomach (40 cc./kg.) or by slow intravenous infusion (25 cc./kg.), they excrete it practically quantitatively within three hours.

2. The water administered by stomach (40 cc./kg.) is completely absorbed from the gastro-intestinal tract in 40 minutes.

3. Morphine, given 40 minutes after the administration of water by stomach or 15 minutes before the intravenous infusion of water is started, inhibits water diuresis very markedly (excreted amount 2-15%).

4. The inhibition of water diuresis due to morphine is accompanied by a percentual and absolute increase in chloride excretion.

5. Morphine either does not inhibit saline diuresis or inhibits it to a lesser degree than it does water diuresis.

6. The adrenaline liberated due to morphine is not involved in the morphine antidiuresis.

7. Morphine does not inhibit water diuresis in diabetes insipidus dogs. It inhibits water diuresis only if a functioning neurohypophysis is present in the animal, the antidiuretic hormone of the neurohypophysis is necessary for the antidiuretic action of morphine.

8. Morphine does not potentiate the antidiuretic action of the circulating posterior pituitary hormone.

9. Morphine brings about the liberation of the antidiuretic hormone by acting on the hypothalamico-hypophysial system.

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