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November 1970

A Humoral Inhibitor of Sodium Transport in Uremic Serum: A Potential Toxin?

Author Affiliations

St. Louis

From the Renal Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis.

Arch Intern Med. 1970;126(5):860-864. doi:10.1001/archinte.1970.00310110130023

A low molecular weight fraction of serum from uremic patients has been found to inhibit several different transport systems. These include the uptake of p-aminohippuric acid (PAH) by rabbit kidney cortical slices, the transepithelial transport of sodium by the isolated frog skin, and finally, sodium reabsorption by the rat kidney tubule. The following possibilities are considered: first, that the substance might be a naturally occurring humoral agent which serves in a homeostatic role to increase sodium excretion rate per nephron as the number of nephrons diminishes in advancing renal disease; and second, that in advanced renal disease, very high levels of this humoral agent could lead to inhibition of sodium transport in extrarenal organs and, thus, could contribute importantly to the symptoms and signs of the uremic state.