Experiments concerning the question of secretion of phenolsulphone-phthalein by the renal tubule

Abstract

Among the most important methods of study which have been applied to the question of secretion by the renal tubule are those which involve the use of dyes. Heidenhain revived the Bowman theory of secretion, largely because of his observations relating to the elimination of indigo carmin—observations which form the beginning of a voluminous and confusing literature. The importance of complete information concerning the mode of excretion of certain dyes can scarcely be denied: they resemble most of the normal urinary con­stituents in that the concentration in which, after injection, they appear in the urine is higher than that in the blood. As has frequently been argued, if the mechanisms which take part in the excretion of these substances can be identi­fied, light will be thrown upon the processes of normal urine formation. The experimental advantage which derives from their colour is obvious. Phenolsulphonephthalein (phenol red) was introduced as a clinical test of renal function by Rowntree and Geraghty( 1 ) in 1912. Among their experi­ments was one which convinced them that the tubule was actively concerned in its elimination. After section of the renal arteries in the frog, a phenol-red solution was perfused through the renal portal vessels at a pressure of 35 cm. water. The resulting appearance of the dye in the ureteral fluid convinced them that it had been “secreted” by the tubule. It was soon shown by Bainbridge, Collins and Menzies( 2 ), however, that such high pressure in the renal portal vessels may drive fluid through the efferent vessels into the glome­ruli; thus their “proof” that the glomeruli had not been involved in the observed excretion was invalidated.