Variations in pigment and carbohydrate content of gallbladder bile affect accurate quantitation of total protein when using the fluorescamine method.
BACKGROUND
Despite solute dilution and reduced total lipid concentrations, an unexplained increase in protein concentration has been reported to occur in the gallbladder bile of cholesterol gallstone patients.


METHODS
Solutes in gallbladder bile from gallstone-free controls and from four study groups were measured using standard methods. Total proteins were measured using amino acid analysis and a conventional fluorescamine method.


RESULTS
Bile salts and pigment content were greater in gallstone-free controls than in all other study groups, including morbidly obese gallstone-free subjects. Total biliary protein concentration, as determined by amino acid analysis in the gallstone-free control group was higher than in non-obese gallstone patients with multiple stones and in morbidly obese gallstone-free subjects. Total biliary proteins as measured with fluorescamine, however, did not show intergroup differences. A major problem of the conventional fluorescamine assay is shown to be an artefact arising from the high pigment content of the more concentrated samples.


CONCLUSIONS
Very dilute gallbladder bile samples are often found in the presence of gallstone disease. This also occurs in morbidly obese subjects, even in the absence of gallstones. Although the contribution of protein secretion/absorption by the gallbladder can also be relevant, especially in the presence of morbid obesity, the protein concentration in gallbladder bile, when accurately measured, generally parallels the concentrations of non-absorbed biliary solutes, reflecting the efficiency of fluid absorption. Measurement of biliary proteins by the conventional fluorescamine method is unreliable in clinical studies in which intergroup differences in pigment content are commonly present.
Ginanni Corradini
S
S
Dept. of Gastroenterology, Cleveland Clinic Foundation, Ohio, USA.
Yamashita
G
G
Nuutinen
H
H
Chernosky
A
A
Williams
C
C
Hays
L
L
Shiffman
M L
ML
Walsh
R M
RM
Svanvik
J
J
Della Guardia
P
P
Capocaccia
L
L
Holzbach
R T
RT
D000328:Adult; D000596:Amino Acids / Q000032:analysis; D001646:Bile / Q000737:chemistry*; D001647:Bile Acids and Salts / Q000032:analysis; D001654:Bile Pigments / Q000032:analysis*; D002241:Carbohydrates / Q000032:analysis*; D016022:Case-Control Studies; D002769:Cholelithiasis / Q000737:chemistry* / Q000175:diagnosis; D002784:Cholesterol / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005450:Fluorescamine; D006801:Humans; D007202:Indicators and Reagents; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000378:metabolism; D011506:Proteins / Q000032:analysis*
D000596:Amino Acids; D001647:Bile Acids and Salts; D001654:Bile Pigments; D002241:Carbohydrates; D007202:Indicators and Reagents; D011506:Proteins; D005450:Fluorescamine; D002784:Cholesterol