SOME CONDITIONS AFFECTING THE BLOOD FLOW THROUGH THE PERFUSED MAMMARY GLAND, WITH SPECIAL REFERENCE TO THE ACTION OF ADRENALINE

Inclusion of the lungs in a circuit for perfusion of the mammary gland makes it possible, by destroying vasotonins, to maintain the gland blood flow at or near its normal values. However, if the passage of blood through the apparatus is slow, more vasotonins form before it reaches the mammary vessels and blood flow is seriously reduced. It is therefore necessary to arrange the system so that there is minimal circulatory delay between lungs and gland. Similar considerations apply to experiments in which the perfused gland is supplied with arterial blood from an anesthetized animal: rapid re-circulation of blood through the animal reduces the vasotonin content of the blood, and the mammary blood flow is much higher than previously observed for prolonged periods of perfusion. In mammary-lung preparations of the dog, cat and goat the mammary blood vessels are exceedingly sensitive to adrenaline, and vasoconstrictor responses are obtained when the amount of adrenaline injected, expressed as g. per g. of tissue, is of the order of 10- 14 .