Inactivation of serum ribonuclease by the kidney

¹ Laboratory for Cell Physiology, Faculdade de Medicina da Universidade de São Paulo, Brasil

The ureterovenous anastomosis preparation (U.V.A.) was used to study the inactivation of serum ribonuclease (RNase) by the kidneys. A significant increase was found in the enzyme activity 2 hours after the operation, with a return to levels close to the initial ones in succeeding periods up to 8 hours. This behavior contrasted with that of bilaterally nephrectomized dogs where activity steeply rose to high levels and was thereafter maintained. The behavior of serum creatinine was similar in both groups of animals. Infusion of urine did not influence the RNase activity increase of nephrectomized dogs. U.V.A. animals, when nephrectomized, were able to respond with increases in serum RNase. Athrocytosis of intravenously injected hemoglobin was observed in U.V.A. dogs. It is suggested that these findings agree with the hypothesis of a mechanism of glomerular filtration plus tubular reabsorption and destruction of part of the plasma RNase.