Plasma Albumin Catabolism in Experimental Nephrosis

Abstract

GLOMERULAR filtration and tubular re-absorption of plasma albumin occur as part of the normal function of the mammalian kidney¹. The fate of the reabsorbed protein is less certain. Oliver et al.² have presented evidence that enzyme systems capable of catabolizing certain of the plasma proteins exist in the renal tubule cell, suggesting that re-absorbed protein is broken down in transit through the cell. However, we have demonstrated that in the normal rat³ and dog⁴, bilateral nephrectomy depresses the breakdown of plasma albumin to only a limited extent. The amount of plasma albumin contained in the renal tubules of rats with experimental nephrosis is much greater than normal, and Goodman and Baxter⁵ maintain that this is due to enhanced glomerular filtration and subsequent tubular re-absorption of greater than normal quantities of plasma protein. We have reasoned that if the kidney has any important role in plasma albumin catabolism it should be demonstrable under these conditions of exaggerated albumin reabsorption.