Role of Dietary Protein in Normal Rat Proteinuria

¹ From the Department of Biochemistry, University of Texas, Southwestern Medical School, Dallas, Texas

A twofold increase in proteinuria, which is produced by raising the dietary content of casein from 12 or 18% to a level of 50%, was duplicated by other proteins fed either singly or in combinations. The type of urinary protein was not electrophoretically altered by the protein fed. Increased urea and water excretion, common factors associated with the intake of the various proteins, were investigated. Urea, either fed or injected, was found to cause a proteinuria similar in many respects to that produced by intact protein. Water loading experiments separated the two factors to show that a much closer parallelism exists between urea and protein excretion than between the latter and urine volume.