Study of indirect methods for measuring hepatic blood flow in the isolated perfused dog liver

This study was undertaken to assess the reliability of the constant infusion clearance and extraction technique (CIT) and the single injection clearance method (SIT), to measure hepatic perfusate flow at different levels of liver function. In the 36 isolated perfused dog livers, hepatic perfusate flow(HPF) was monitored by a direct method (DM), and the HPF was simultaneously measured with an indirect method (IM) utilizing bromosulphophthalein BSP) as indicator (20 SIT and 16 SIT). In 16 experiments, absolute ethanol (750 mM) and sodium taurocholate (600 muM) were seperately utilized to impair BSP metabolism. By comparison with DM, in the experiments with an extraction ratio(ER) of BSP lower than 10%, the error of the IM (ml/min) was for the CIT 154.57 +/- 46.55 and for the SIT 107.25 +/- 34.20. This error was significantly greater than in the experiments with an ER greater than 10% (CIT 15.70 +/- 3.88, SIT 8.20 +/- 1.38) p less than 0.01. In the studies with ER less than 10%, no difference was found in the error detected with the SIT (107 +/- 34.20) and CIT measurements (154.37 +/- 46.55); in the experiments with an ER greater than 10%, the error with the CIT (15.70 +/- 3.88) was greater than the one attained with the SIT (8.20 +/- 1.38, p less than 0.10 greater than 0.05). It is concluded that both methods are reliable techniques, for measuring HPF in livers with normal or near normal clearance capacity, but even in these ideal experimental conditions the values for HPF are inacurate when the liver clearance function is moderate or severly impaired.