A simplified isolated perfused rat liver apparatus: characterization and measurement of extraction ratios of selected compounds

Effect of erythrocytes on the hepatic distribution kinetics of antipyrine

The role of erythrocyte on the hepatic distribution kinetics of antipyrine was investigated in the in situ isolated perfused rat liver. Perfusion experiments were conducted using Krebs-bicarbonate buffer delivered via the portal vein in a single pass mode at a total flow rate of 15 ml/min. A bolus dose of antipyrine was administered in the presence and absence of erythrocytes. Almost identical moment analysis results (without erythrocytes mean transit time, MTT: 23 s; volume of distribution, VH: 0.57 ml/g liver and with erythrocytes, MTT: 24 s; VH: 0.60 ml/g liver) and superimposable unimodal effluent curves were obtained in the presence and absence of erythrocytes indicates that distribution kinetics of antipyrine within the liver is not affected by erythrocytes.

Evaluation of liver functional reserve by combining D-sorbitol clearance rate and CT measured liver volume

AIM: Our research attempted to evaluate the overall functional reserve of cirrhotic liver by combination of hepatic functional blood flow, liver volume, and Child-Pugh’s classification, and to discuss its value of clinical application.

METHODS: Ninety two patients with portal hypertension due to hepatic cirrhosis were investigated. All had a history of haematemesis and hematochezia, esophageal and gastric fundus varices, splenomegaly and hypersplenia. A 2-year follow-up was routinely performed and no one was lost. Twenty two healthy volunteers were used as control group. Blood and urine samples were collected 4 times before and after intravenous D-sorbitol infusion. The hepatic clearance (CL_H) of D-sorbitol was then calculated according to enzymatic spectrophotometric method while the total blood flow (Q_TOTAL) and intrahepatic shunt (R_INS) were detected by multicolor Doppler ultrasound, and the liver volume was measured by spiral CT. Data were estimated by t-test, variance calculation and chi-squared test. The relationships between all these parameters and different groups were investigated according to Child-Pugh classification and postoperative complications respectively.

RESULTS: Steady blood concentration was achieved 120 mins after D-sorbitol intravenous infusion, which was (0.358 ± 0.064) mmol·L^-1 in cirrhotic group and (0.189 ± 0.05) mmol·L^-1 in control group (P < 0.01). CL_H = (812.7 ± 112.4) mL·min^-1, Q_TOTAL = (1280.6 ± 131.4) mL·min^-1, and R_INS = (36.54 ± 10.65)% in cirrhotic group and CL_H = (1248.3 ± 210.5) mL·min^-1, Q_TOTAL = (1362.4 ± 126.9) mL·min^-1, and R_INS = (8.37 ± 3.32)% in control group (P < 0.01). The liver volume of cirrhotic group was 1057 ± 249 cm³, 851 ± 148 cm³ and 663 ± 77 cm³ in Child A, B and C group respectively with significant difference (P < 0.001). The average volume of cirrhotic liver in Child B, C group was significantly reduced in comparison with that in control group (P < 0.001). The patient, whose liver volume decreased by 40% with the CL_H below 600 mL·min^-1, would have a higher incidence of postoperative complications. There was no strict correspondent relationship between CL_H, liver volume and Child-Pugh’s classification.

CONCLUSION: The hepatic clearance of D-sorbitol, CT measured liver volume can be reliably used for the evaluation of hepatic functional blood flow and liver metabolic volume. Combined with the Child-Pugh’s classification, it could be very useful for further understanding the liver functional reserve, therefore help determine reasonable therapeutic plan, choose surgical procedures and operating time.

Measurement of disposition half-life, clearance, and residence times

This unit provides an overview of the principles underlying the elimination process. Experimental design issues, methods of data analysis, and complications that may be encountered are discussed. A complete worked example is provided to exemplify the methods of analysis that are available.