Necessity of a 3-compartmental model for analyzing the distribution and excretion kinetics of i.v. injected bile acids in man.

The distribution and excretion of i.v. injected c14-glycocholate (n = 8) and c14-cholate (n = 5) was measured in the serum, duodenal juice and urine in 13 patients in order to examine the possibilities to reporduce the measured data by a multi-compartmental analysis. The results demonstrate that a 3-exponential fitting and therefore a 3-compartmental model represents at present the most appropiate compartmental model for analyzing the distribition and excretion kinetics of the injected bile acids by mathematical procedures. In extending the previously described 2-compartmental model it encloses the 3-compartments plasma, liver and extrahepatoplasmatic space and allows a precise calculation of important physiological parameters, for example of the hepatic (V1/V2-clearance) and extrahepatoplasmatic (V1/V3-clearance) clearance, the biliary excretion and the distribution between the 3 compartments.