Effect of hemorrhage and vasopressor agents on distribution of renal blood flow.

RECTOR, JAMES B., JAY H. STEIN, WILLIAM H. BAY, RICHARD W. OSGOOD, AND THOMAS F. FERRIS. Effect of hemorrhage and vasopressor agents on distribution of renal blood jaw. Am. J. Physiol. 222(5) : 1125-1131. 1972.-Studies were performed in the dog in which the distribution of renal cortical blood flow was determined with the radioactive microsphere method. Three experimental models were evaluated: 1) hemorrhagic hypotension, 2) intrarenal in&rsion of norepinephrine (4 pg/min), and 3) intrarenal infusion of ngiotensin (100 ng/min). In all I o hemorrhage studies, there was t marked alteration in the distribution of blood flow with a de.:rease in flow to outer cortical nephrons and a concomitant increase in the fraction of flow to inner cortical nephrons. In 11 studies, norepinephrine decreased total blood flow 49%, but had no effect on the fractional distribution of blood flow. Similarly, in 12 studies angiotensin II decreased total blood flow 41%, but there was no alteration in zonal distribution of blood flow. In a separate series of experiments, a comparison was made of the change in total renal blood flow, vascular volume, and mean transit time as measured by the indocyanine green indicatordilution technique during hemorrhage and norepinephrine administration. There was no significant difference in the decrease in total blood flow and vascular volume or the increase in transit time between the two experimental maneuvers. Therefore, these results indicate that there are definite differences in the distribution of cortical blood flow during hemorrhage and vasopressor infusion and that the redistribution of flow which occurs during hemorrhage is not due to the humoral release of either norepinephrine or angiotensin.