Filtration and reabsorption of protein by the kidney.

Plasma proteins of the rat have been labelled by the in vivo injection of the dye T-1824. From a study of the rate of disappearance of T-1824 from the circulating blood, and the total T-1824 content of the perfused kidney the rate of protein reabsorption from the glomerular fluid by the cells of the renal tubule has been calculated. It is concluded that protein reabsorption by the cells lining the proximal convoluted tubule of the rat kidney proceeds at a rate of at least 5 mg. per hour, equivalent to a daily filtration and reabsorption of 33 per cent of the circulating plasma protein.