Abstract
Although Ott and Scott 1 demonstrated that an extract of the posterior hypophysis would cause an ejection of milk from the alveoli of the mammary gland this phenomenon was not associated with the natural let clown of milk until the work of Ely and Petersen, 2 who demonstrated that both the oxytocic and vasopressor substances of the posterior pituitary would cause an ejection of milk in the cow. Turner and Cooper 3 reported the same for the rabbit. Ely and Petersen observed fright or the injection of epinephrin inhibited the natural response to the milking” stimulus. Petersen and Ludwiek 4 showed that the substance responsible for the ejection of milk is humoral in nature and that the blood from excited cows has great vasoconstricting properties in perfused bovine mammary glands.
As a result of these observations, it was deemed advisable to test the effects of a number of substances upon the blood flow and the milk ejection mechanism in the bovine mammary gland. This report deals with 9 substances: oxytocin, pitressin, epinephrin, his-tamine, atropine, ergonovine, acetylcholine, Mecholyl (acetyl-β-methylcholine) and Lentin (carbamylcholine).
The experiments here reported were on bovine mammary glands perfused according to the technic of Petersen, Shaw and Visscher. 5 The glands were obtained from a packing plant. The teats were cannulated to permit drainage of the milk immediately after the perfusion started and the cannula left in situ during the experiment. The blood pressure was maintained at 110 mg Hg pressure at all times. The substances tested were injected into the arterial blood as it entered the gland.
The number of experiments, dosage of the substance, effect on the blood flow and the effect on the ejection of milk are given in Table I for each substance tested.
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