The Effect on the Rate of Urea Excretion of Carmine Deposition in the Cells of the Renal Tubules

The evidence that urea is present in high concentration in the cells of the convoluted tubules of the kidney and is passing through these cells has been reviewed. Following the deposition of a large amount of carmine in the cells of the convoluted tubules the rate of urea excretion, as measured by the relation of the rate of urea excretion to the blood urea concentration, is increased. This is interpreted as due to blockage or damage to the cells of the convoluted tubules which interferes with their usual function of absorption of urea and other substances from the glomerular filtrate and hence increases the amount of urea which reaches the bladder urine at a given blood urea concentration.