DEPOSITION OF DYES, IRON AND UREA IN THE CELLS OF A RENAL TUBULE AFTER THEIR INJECTION INTO ITS LUMEN: GLOMERULAR ELIMINATION OF THE SAME SUBSTANCES

Abstract

Since Heidenhain''s experiments many students of renal physiology have considered the presence of dye in the cells of the convoluted tubules following intravenous injection as evi dence favoring the secretory function of these cells. Others have inclined toward Sobieranski''s opinion that the staining might result from reabsorption of a dye-containing filtrate from the lumen of the tubule. Evidence as to the validity of opinions based on the histo-logical picture of fixed sections of the kidney after injection of dyes into the blood stream was sought by comparing results obtained with frogs after intravenous (or lymph sac) injection with those following introduction of a dye directly into the lumen of a tubule by injecting it into Bowman''s space. The intracapsular injections were made by Wearn and Richards'' method. Indigo carmine, sodium carminate, methylene blue, trypan blue, toluidin blue, phenolsulphonephthalein, Fe salts and urea were used. Intravenous and intracapsular injections yielded similar staining of tubule cells in all cases. All substances tested are present in the glomeru-lar fluid following intravenous injection. It is believed that presence of dye in the tubule cells following intravenous injection is no better evidence of secretion than of reabsorption, and that possibly it is evidence of neither.