DISTRIBUTION OF BLOOD IN THE RABBIT'S KIDNEY

Abstract

Trueta has postulated that the blood reaching the kidney has 2 potential routes through that organ, and according to circumstances it may pass almost exclusively by 1 or the other. He recorded no measurements of blood flow and few of blood pressure. Rabbits under Na pentothal anesthesia were eviscerated and prepd. for measurement of renal blood flow by a modified Brodie technic. Blood pressure was recorded from a carotid cannula attached to a Hg manometer. The glomeruli receiving blood were stained with Janus green injd. into the stump of the superior mesenteric artery. Under control conditions either all glomeruli were stained, or those unstained were scattered irregularly through the peripheral and mid zones of the cortex. In a certain number of expts. in which renal blood flow or systemic blood pressure or both were reduced following stimulation of the sciatic nerve or renal artery or by hemorrhage, only the juxtamedullary glomeruli were stained. In no expt. were the peripheral glomeruli stained and the juxtamedullary unstained. Perfusion of the excised kidney with Berlin blue in 6% acacia at 50 cm. water pressure injects all glomeruli. As the perfusion pressure is reduced the peripheral glomeruli are not injected. When the perfusion pressure is about 20 cm. water, only the juxtamedullary glomeruli are injected. These expts. lend no support to the conception that a normal renal blood flow can be diverted or shunted through cortical or medullary channels. When renal blood flow or blood pressure is reduced under certain conditions, the juxtamedullary glomeruli are preferentially perfused. The lower resistance of these channels would appear to be one factor.