THE EFFECT OF HEMOGLOBIN ON VOLUME OF THE KIDNEY

Abstract

In plethysmo-graphic studies to determine which portion of the laked erythrocyte exerted a vasoconstrictor action on the vessels of the kidney, transient decrease of volume of the kidney was recorded following intravenous injections of distilled water, laked blood, and Hb. The injections of stroma suspension of the erythrocytes produced slight increase of volume of the kidney or were without effect. With no decrease in volume of the spleen, and with carotid blood pressure constant throughout the experiments, it may be concluded that Hb is the constituent of the erythrocytes which exerts a specific vasoconstrictor action on the renal blood vessels. This contraction was produced whether Hb itself was introduced into the circulation or whether it was liberated as the result of in vivo laking of erythrocytes. To determine the mode of action of this vasoconstrictor fraction the kidney of the frog was directly observed following intravenous administration of Hb; it appeared that decrease of volume of the kidney resulted from generalized contraction of renal arterioles. Further evidence was obtained from plethysmographic records following injection of large amounts of distilled water and laked blood. There was always a primary response of the kidney with typical constriction curves and an attempt to recover the original volume despite slow continued administration of the test substance. Increased speed of injection was promptly followed by secondary transient decreases of kidney volume. This seems to indicate that the renal vessels tolerate a certain amount of free Hb in the blood stream, but that when this amount is increased above a certain threshold they respond with contraction.