Influence of aortic constriction on the positive free-water clearance of primate hemorrhagic shock.

Abstract

SummaryPositive free-water clearance, signifying production of hypotonic urine, is commonly observed in well-hydrated owl monkeys following transfusion of shed blood after prolonged hemorrhagic hypotension. This investigation has examined the nature of this derangement of the urinary concentrating mechanism by experimental reduction of glomerular filtration rate by partial aortic constriction during this phase of experimental shock, and in turn, diminution of solute and water load to the nephron. When the resulting reduced volume was delivered to the final concentrating segment, removal of only a small portion of the residual volume was necessary for the elaboration of a urine of higher solute concentration, approaching that of plasma, so that U/Posm which was well below 1.0 immediately after transfusion was restored close to unity.