Abstract
A kidney is drawn out of the body cavity of a dog and sutured under the skin of the back, with the renal vein located in such a position that it can be punctured through the skin with a needle. The metabolism of the kidney has been studied by simultaneous analyses of arterial and renal bloods and of urine secreted during the observation periods. The rate of blood flow through the kidney has been estimated by comparing the amount of urea removed from a unit volume of blood in passing through the kidney with the amount excreted per minute. In most of our experiments only one kidney at a time has been studied; one is brought out under the skin, and the other is removed, in order to simplify the experiments. In a few controls in which one kidney was brought out and the other left in situ excretion was similar in both.
Through a single kidney in clogs of 15 to 20 kilos weight the blood flow is in the neighborhood of 200-250 cc. per minute. Increasing the urea content of the blood as much as 10-fold does not significantly accelerate the blood flow. The urea excretion increases 10-fold, but the increase is due to the fact that the proportion of blood urea removed during perfusion of the kidney remains constant, so that the amount removed per liter of blood passing through the kidneys rises in proportion to the amount present in the blood. This explains the manner in which the blood urea clearance is kept constant during wide fluctuations in blood urea content.
The proportion of oxygen removed from the blood by the kidney is rather low, 10 to 20% of the arterial oxygen content as a rule.
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