The milk-ejecting potencies of deamino-oxytocin and oxytocin were compared by means of recordings of intramammary pressure in lactating women.
No difference in milk-ejecting potency was found between the two peptides in one woman 16 months after delivery; at this time her blood did not inactivate either of the peptides.
In other women on the third day post partum, deamino-oxytocin was found to be 1·5 times as potent as oxytocin (w/w). At this stage, the blood of the patients inactivated oxytocin (half life: 10 min.) but not deamino-oxytocin; this effect accounts only in part for the difference in potency between the two peptides.