"558 XI. HEMOGLOBIN CATABOLISM, I 



2^^). Royer {2379,2380,238^,2387) studied this phenomenon in dogs. By 

 estimations of urobihn by the zinc salt fluorescence method in the arterial 

 and venous blood, he found that not only the liver and kidney, but also 

 spleen, pancreas, and muscles absorbed urobilin from the blood stream; even 

 after removal of all abdominal organs the greater part of the injected urobilin 

 disappeared. Forty-five minutes after the injection of 10 mg. urobilin per kg., 

 60% of it could be found in the liver, kidney, and muscles. Later it dis- 

 appeared from the viscera, but apparently not from the muscles. Injection 

 of India ink retarded the removal of the last traces of urobilin from the blood, 

 indicating that reticuloendothelial cells played a part in the removal of 

 urobilin {cf. al.so 2983,3101). 



Royer did not determine urobilinogen and it is therefore uncertain whether 

 the observed disappearance of urobilin from the organs and also partly from 

 the blood might not have been due to reduction. Watson (2983) found 50 mg. 

 injected /-tetrahydromesobilene to disappear from the blood of the dog in 

 40 minutes (both urobilin and urobilinogen); he does not assume absorption 

 by tissues other than liver or kidney. It is questionable whether these experi- 

 ments have a physiological significance. Even if exceptionally large amounts 

 of urobilin are reabsorbed from the intestine, its concentration in the blood 

 would hardly reach a level comparable to that after a sudden injection. 

 Normal muscles have not been found to contain urobilin, and the effect of 

 liver damage on urobilinuria would be difficult to understand, if the muscles 

 had a great potentiality for absorbing urobilin under physiological conditions. 

 It is also hardly justifiable to draw conclusions from such experiments, with 

 regard to the rate of removal of urobilin from the blood stream by the liver. 



In urobilinemia urobilin passes into transudates and exudates (3100,3101). 



After extirpation of the liver urobilinemia develops, but the excretion of 

 urobilin in the urine is not increased; neither is the increase of urobilinuria, 

 after creating a by-pass from the portal vein to the vena cava (Eck fistula) 

 thus short-circuiting the liver, as high as would be expected (490,2379); 

 since urobilin injected intravenously into dogs so treated also does not cause 

 an increase of urobilinuria, the absence of such increase must be due to renal 

 damage. 



9.2.6. Urobilinuria. The normal daily urinary excretion of uro- 

 bilin varies between and 3.5 mg. per day and is usually between 

 0.5 and 1.5 mg. (2990), i.e., below 1% of the total urobilin excretion. 

 It is subject to large diurnal variations and is increased after meals 

 (2417) or by constipation, and decreased by laxatives (cf. Section 

 9.1.2.). Royer and Solari (2389) found that both glomerulus and 

 tubules excrete urobilin in man, while in the dog only the glomerulus 

 did so. Kidney disease can decrease or prevent urobilin excretion in 

 the urine. 



Damage of the liver causes an increase of the excretion of urobilin 

 in the urine; this is probably the most sensitive sign of liver damage, 

 appearing in jaundice before bilirubinuria can be noticed, although 



