Effect of hemorrhage and retransfusion on intrarenal distribution of blood flow in dogs

Abstract

A B S T R A C T Distribution of intrarenal blood flow was studied in 12 dogs anesthetized with Nembutal. Medullary blood flow was estimated by local clearance of hydrogen gas from the outer medulla measured polarographically with needleshaped platinum electrodes, and by local clearance of 85Kr and mean transit time of 32P-labeled erythrocytes measured with a small semiconductor detector placed in the outer medulla. Cortical blood flow was estimated from cortical red cell transit time and from total renal blood flow measured by electromagnetic flowmeter.Bleeding to a mean arterial pressure of 50-65 mm Hg in the course of 8-20 min reduced cortical and medullary blood flow on the average to the same extent. In half of the experiments both cortical and medullary blood flow were reduced proportionately less than mean arterial pressure during the first half hour of bleeding. Maintenance of mean arterial pressure at 50-65 mm Hg in all cases led to progressive reduction of both cortical and medullary blood flow, out of proportion to the reduction of arterial pressure. A two step bleeding procedure used in two experiments also led to uniform reduction of renal blood flow. Reinfusion of blood after 2-3 hr of hypotension increased total renal blood flow to an average of 82% and outer medullary hydrogen clearance to an average of 92%o of control values. All dogs survived the experiment without evidence of renal failure.

Role of the sympathetic nervous system in the renal response to hemorrhage

“…This hypothesis is based on the reports that hemorrhagic hypotension decreased blood flow through the superficial cortex but had little effect on blood flow through the juxtamedullary area (19,20). More recent studies, however, indicate that hemorrhagic hypotension decreases cortical and medullary blood flow to the same extent and thus do not support the concept of a selective resistance of the juxtamedullary circulation to hemorrhage (21). Conceivably, glomerular filtration rate could increase in the juxtamedullary area relative to the superficial cortical area in response to hemorrhage despite a comparable decrease in blood flow in the two areas.…”

Effect of renal vasodilatation on the distribution of cortical blood flow in the kidney of the dog

“…In zone 1 there was a marked decrease in the per cent of renal blood flow from 45 ±2 to 33 +2% (P < 0.001). There was no change in zone 2 whereas both FIGURE 3 Comparison of the fractional distribution of blood flow in the same area of the cortex after the injection of two different radioactive microspheres. The corresponding cortical zone for each point is given.…”

“…Aukland and Wolgast used a technique in which blood flow is measured with a hydrogen-sensitive electrode placed in different areas of the cortex (3). With this technique these authors found no alteration in the distribution of renal blood flow during hemorrhagic hypotension in sharp contrast with the results of Carriere, Thorburn, O'Morchoe, and Barger using the 'Kr technique (4).…”

Effect of retransfusion after hemorrhagic hypotension on intrarenal distribution of blood flow in dogs

“…The cortical ischemia observed during the hypotensive period (10-13) readily explains the reduced renal blood flow since the outer medullary blood flow is relatively well maintained during hemorrhagic hypotension (11,12). This last point, however, is still subject to controversy (10,13).…”

“…The data concerning the intrarenal distribution of the blood flow after restoration of blood pressure following hemorrhagic hypotension are sparse (12,13) and incomplete. In these studies, no definite conclusions could be established concerning the modifications of the cortical circulation because of the inconsistent results obtained in a small number of experiments.…”