126 
Scientific Proceedings (44). 
76 (601) 
The behavior of fat-soluble dyes in the organism. 
By LAFAYETTE B. MENDEL and AMY L. DANIELS. 
[From the Laboratory of Physiological Chemistry, Sheffield 
Scientific School, Yale University, New Haven, Conn] 
It is well known that the fat-soluble dye, Sudan III., is readily 
deposited in the adipose tissue of animals. An attempt was made 
by the authors to study the movements of the dye under conditions 
where fat transport takes place (e. g., in starvation, phlorhizin- 
and phosphorus poisoning). The dye readily migrates into the 
blood with the fat under these conditions, but is rarely found in the 
liver tissue into which large quantities of fat enter (fatty infiltra- 
tion). This is explained by the observation that the Sudan III. 
is abundantly excreted with the bile into the intestine from which 
it may be reabsorbed. Sudan III., which is insoluble in water, 
is not excreted through the kidneys except where alimentary 
lipuria is induced (in rabbits and rats). The elimination from 
the liver is not accomplished through the solvent medium of fat 
excreted in the bile (lipocholia) ; but the dye is soluble in bile as 
well as in solution of the isolated bile salts. We have thus estab- 
lished a path of elimination for fat-soluble (or bile-soluble) substances 
through the biliary secretion. An investigation of a considerable 
number of water-insoluble, fat-soluble compounds — mostly non- 
toxic aniline dyes and food colors — showed comparable conditions 
justifying the above general conclusion. It has further been 
established that these water-insoluble compounds do not experi- 
ence absorption from the intestine in the absence of bile. Dis- 
solved in fat-emulsion and introduced into the organism by ali- 
mentary, subcutaneous, or intravenous paths, these dyes are al- 
ways eliminated with the bile into the intestine. When there is 
a paucity of fat in the diet the fat-soluble dyes may be absorbed 
through the agency of reabsorbed bile, but they are speedily 
eliminated again by the liver channels; with an abundance of 
fat to act as carrier, they travel with it through the lymphatics 
into the circulation. The distribution of fat-soluble dyes within 
the organism depends on the presence of fat and its migrations. 
