ON THE ACTIVE PRINCIPLES OF THE PITUITARY GLAND

¹ From the Department of Biochemistry and Pharmacology, National Institute for Medical Research, London

1. An attempt has been made by various methods to effect a purification of the oxytocic principle of the posterior lobe of the pituitary gland.

2. A crystalline picrate was obtained which had the characteristic actions of pituitary extracts on plain muscle and blood pressure. It had an activity of the same order as that of histamine. It was found to be the picrate of an inert substance merely contaminated with small amounts of the pituitary principles, and was eventually identified as potassium creatinine picrate.

3. Out of the mother liquor from the recrystallization of this potassium creatinine picrate a small alcohol soluble residue was obtained. This yielded an acetone insoluble A and an acetone soluble R fraction. A had an oxytocic activity equal to about twelve times that of histamine (reckoned as base), producing a definite contraction of the uterus in a dilution of 1 part in 1,250,000,000. A also contained a pressor principle, displaying no preliminary depressor activity. It produced a strong rise of blood pressure in a dose of 0.01 mgm. R, had one-twentieth the oxytocic activity of A, and in doses of 0.5 mgm. produced a strong depressor action followed by a moderate pressor action on the blood pressure.

4. Evidence is put forward to show that the oxytocic and pressor principles of A are two separate chemical individuals, and that the pressor principles of A and R are most probably also two, distinct chemical entities.

5. It is considered, therefore, that there is valid evidence for the presence of at least three different physiologically active principles in pituitary extracts. Since this view is in direct conflict with that of Abel and Rouiller a criticism of their recently published conclusions is presented.