[Measure of splanchnic blood flow by marker dilution: comparison of 4 methods of para-aminohippuric acid determination].

The objective of this study was to determine the influence of the analytical method of para aminohippuric acid (PAH) on splanchnic blood flows, as measured by a dye dilution method in ovines. Four different analytical methods of PAH were compared. They differed in the pretreatment of the samples and in the presence or absence of a deacetylation step to account for the partial acetylation of PAH in the liver (13%). The optimum conditions of deacetylation were defined as 60 min of incubation at 90 degrees C in presence of HCl (5N). The four analytical methods were checked to be linear (from 0 to 35 mg/L), repeatable (CV = 0.70%) and reproducible (CV = 2.1%). It appeared necessary to prepare the standards in the same matrix as that of the samples. The choice of the analytical method was responsible for differences in PAH concentrations and in the absolute values for portal and hepatic blood flows, which could reach 21%. The presence of a deacetylation step with HCl significantly reduced the contribution of the hepatic artery to the total hepatic blood flow (from 24 to 10%). Consequently, this study showed that the nature of the analytical method chosen can highly influence the measurements of splanchnic nutrient fluxes. The recommended analytical method is the one which includes a deacetylation step.