Role of ADH in the Loss of Renal Concentrating Ability in Primate Hemorrhagic Shock 1

Abstract

Summary

Positive free water clearance (C_H2o), signifying production of hypotonic urine, is produced in the normally hydrated owl monkey after prolonged hypotension when hemorrhaged blood is transfused, and U/P _osm less than unity is typically seen. Assay of plasma vasopressin showed marked increases after 2 hr of hypotension. After transfusion, concentrations still averaged twice the control value, demonstrating that the loss of concentrating ability of the collecting duct at this time was not due to inadequate ADH production and release. Moreover, when vasopressin was infused intra–ar–terially posttransfusion in amounts far in excess of those needed to inhibit water diuresis (6.5 mU/min/kg), no significant effects were observed on positive free water clearance, nor did experimentally reduced U/P _osm improve significantly during infusion. Thus, prolonged hypotension had resulted in a type of vasopressin (ADH) resistant failure of the concentrating segment of the nephron.