ACID-BASE AND ELECTROLYTE REGULATION IN THE BOVINE GALL-BLADDER BILE MODEL

Design: The relationship between solute and solvent in bile is importa nt for the determination of the likelihood of precipitation of bile co nstituents and, therefore, gallstone formation. Materials and methods: The effect of concentration and acidification on the ionic compositio n of bile and calcium salt solubility was studied in 47 bovine gall bl adder bile samples obtained anaerobically immediated after death. Resu lts: Bovine bile composition is similar to that of human bile. Biliary pH showed a linear reverse relationship with sodium concentration abo ve 200 mmol/l, a linear positive relationship with chloride and revers e linear relationship with total calcium and potassium. Osmolality rem ained constant across a wide range of solute concentrations. Of the bi te samples with pH >7.10, 60% were supersaturated with calcium carbona te, but only 4% with calcium phosphate; there was also a positive rela tionship between the saturation indices for those salts and pH. Conclu sions: The formation of calcium carbonate crystals which serve as a ni dus for gallstone formation is favoured in alkaline bile. Bovine bile allows the integrated study of normal bile and provides a good model f or the study of gait bladder bile physiology, particularly in relation to acid-base and electrolyte regulation.