Glucose Infusion Through the External Pudic Artery. ∗

Abstract

In previous work the amount of lactose in the milk of cows was reduced following partial depletion of the blood glucose through the administration of insulin. 1 This led to attempts to study the effect of increased blood sugar levels upon the amount of lactose in the milk. All attempts at increasing the blood sugar for any period of time failed when glucose was injected intravenously. 2 Intramam-mary duct injections of glucose solutions were also used but resorption of glucose by this method also failed to increase the blood sugar. 3

To study the effect of increased blood sugar upon the quantity of lactose formed in the milk it became apparent that the additions of glucose must be made to the arterial blood and preferably immediately before entering the mammary gland. If glucose is added to the arterial blood of the external pudic artery, the arterial blood passing through the mammary gland will be augmented to the extent of the addition. Accordingly, the technique described by Boyd and Petersen 4 was employed to secure puncture of the external pudic artery and isotonic solutions of glucose were infused over periods up to 6 hours in duration.

The infusion was effected by elevating the aspirator to cause flow by gravity. During the infusion the experimental subject was milked at frequent intervals and the urine was sampled for analysis. As the infusion was performed on the right side of the udder the milk from the left side served as a check as well as the samples before the experiment.

The lactose contents of the milks for both halves of the udder are given for: (a) the average of 3 days'preliminary milkings, (b) 3 milkings during the experiment, and (c) the next 2 milkings following the experiment.

It is to be noted that there is from a slight to a significant increase of lactose in the milks following the experiment and varied effects upon the lactose during the infusion. As the effects are the same for both halves of the udder the results cannot be attributed to the increased glucose content of the blood.

In a few cases the blood sugar was determined upon the venous blood secured from mammary vein punctures close to the udder. The total sugar content varied from 206 to 361 mg. %. All experiments were accompanied with marked diuresis. The total reducing sugar content of the urine, according to the Tauber and Kleiner method, 5 reached a high in the middle of experiment 2. At this point there were 1.5% total sugar and 0.308% lactose. The urine before the experiment averaged .110 total reducing sugar and .064% monose.

It is apparent from the data presented that the lactose content of milk is not increased by increasing 1 the glucose content of the arterial blood. Milks following the perfusion experiments have increased lactose contents that must be explained on some other basis than the effect of increased glucose content of the blood.