THE CLEARANCE, EXTRACTION PERCENTAGE AND ESTIMATED FILTRATION OF SODIUM FERROCYANIDE IN THE MAMMALIAN KIDNEY. COMPARISON WITH INULIN, CREATININE AND UREA

Abstract

In the dog, Na ferrocyanide, inulin, and creatinine showed the same excretory behavior in the following respects (1) Their plasma clearances are approximately equal; (2) their % extractions from the plasma are also approximately equal, averaging approximately 20; (3) their clearances and extraction percentages are independent of plasma concn. The clearance of urea averaged 0.57 of the clearances of the above 3 substances, and was similarly independent of plasma concn. The above observations, taken with the histochemical evidence of Gersh that ferrocyanide is excreted entirely by glomerular filtration, appear to support the filtration-reabsorption theory of renal excretion. Interpreted in accord with this theory, the observations lead to the following conclusions: (1) The plasma clearance of ferrocyanide, inulin, or creatinine in the dog is equal to the glomerular filtrate; (2) from each cc. of plasma entering the glomeruli, on the average 1/5 of the water and of the filterable solutes is filtered; (3) the volume of blood plasma flowing per min. through the kidneys of dogs averages about 5 times the glomerular filtrate, or the plasma clearance, of sodium ferrocyanide, inulin, or creatinine; (4) of the filtered urea, on the average about 43% is reabsorbed.