Structural and functional integrity of rat liver perfused in backward and forward directions.

The purpose of this study was to assess if reversal of the direction of isolated rat liver perfusion would cause significant alterations in hepatic functions and structure. Five isolated rat livers were perfused forward and another five backward with oxygenated Ringer's solution for up to 90 min (hydrostatic pressure: less than or equal to 13 cm H2O; flow rate: forward 3.88 +/- 0.34 ml/min per gram and backward 3.76 +/- 0.34 ml/min per gram). At the end of the experiment, livers were perfusion-fixed for morphological examination. The following results were obtained: No significant differences were noted between the forward and backward perfusions with respect to oxygen uptake, mean bile flow (forward 0.57 +/- 0.12; backward 0.60 +/- 0.14 ml/min per gram), average bile acid excretion (forward 2.39 +/- 1.11; backward 2.83 +/- 0.94 nmol/min per gram), hydroxylation pattern of bile acids, urea synthesis, release of lactic dehydrogenase, glucose secretion, and redox ratios. Light and electron microscopy, including morphometry of parenchymal and sinusoidal areas, revealed that the backward perfusion caused a greater degree of sinusoidal distension, but no other noteworthy differences. Hepatic ultrastructure was well preserved. We conclude that reversing the direction of perfusion does not alter structure and major hepatic functions significantly.