Albumin influences sulfobromophthalein transport by hepatocytes of each acinar zone

Abstract

To determine whether profiles of decreasing concentration were generated among hepatocytes of the liver acinus during the transport of sulfobromophthalein sodium (BSP), rat livers were perfused with various concentrations of this dye (10 microM to 1 mM) in the presence and absence of albumin. After steady-state conditions for the biliary secretion of BSP had been attained, pieces of liver were rapidly frozen. Following the alkalinization of cryostat-cut sections, the relative concentration of BSP in hepatocytes of each zone and the effect of albumin on this localization were quantitated by microspectrophotometry. The results showed that BSP, perfused in the absence of albumin, was efficiently extracted by the liver (95% on a single pass), generating distinct profiles of decreasing cellular concentration from zone 1 to zone 3 at every concentration of BSP. However, the addition of albumin to the perfusate greatly reduced the extraction of BSP from the sinusoidal compartment and resulted in the abolition of the differences in BSP content between hepatocytes of zone 1 and zone 3. These results represent a direct demonstration that, as predicted by mathematical modeling, binding of BSP to albumin indeed results in a more homogeneous distribution of BSP within the liver acinus. A simple and direct microspectrophotometric method is therefore available to follow the changes in the relative concentration of BSP among the hepatocytes of the various acinar zones.

The Isolated Perfused Rat Liver and its use in the Study of Chemical Kinetics: Quality and Performance Parameters

“…Metabolic zonation in the liver has been observed for oxygen consumption (Matsumura et al, 1986), bromosulfophthalein (BSP) metabolism Gumucio et al, 1984;Zhao et aL, 1993), and benzoic acid metabolism (Chiba et aL, 1994). Besides information on the rate of uptake and rate of biliary excretion of a chemical by the liver, potential toxic effects on liver performance can be studied, e.g.…”

“…Data concerning BSP and protein binding (Weisiger, 1993;Pfaff et al, 1975;Gumucio et aL, 1984), plasma membrane transport (Wolkoff, 1993;Tiribelli et al, 1978), liver metabolism and bile excretion (Sathirakul, 1994) are available in the literature. Kinetics of BSP and BSP analogues have been studied using the IPRL system.…”

Summer Research Program - 1998 Summer Research Extension Program Volume 1 Armstrong Laboratory

“…Previous related studies have focused on the BSP uptake rate for exposure of the elasmobranch liver to a fixed, unvarying concentration of chemical in a single pass perfusion system (Weisiger et al, 1984) or on the 1 st pass extraction fraction (Goresky, 1964;Gumucio et al, 1984;Orzes et al, 1985). The study presented here examined the effect of non-equilibrium binding between bovine serum albumin (hereafter referred to as albumin) and BSP on the uptake of BSP by the rat liver, which like other mammalian livers has a much greater BSP uptake rate than the elasmobranch liver.…”

Summer Research Program - 1998 Summer Faculty Research Program. Volume 2. Armstrong Laboratory

“…Previous related studies have focused on the BSP uptake rate for exposure of the elasmobranch liver to a fixed, unvarying concentration of chemical in a single pass perfiision system (Weisiger et al, 1984) or on the 1 st pass extraction fraction (Goresky, 1964;Gumucio et al, 1984;Orzes et al, 1985). The study presented here examined the effect of non-equilibrium binding between bovine serum albumin (hereafter referred to as albumin) and BSP on the uptake of BSP by the rat liver, which like other mammalian livers has a much greater BSP uptake rate than the elasmobranch liver.…”

“…In this work, the anion bromosulphophthalein (BSP) was studied in isolated perfused rat livers in the which the equilibrium concentration of free chemical is predicted to be equal, it is found that the uptake rate is dependent on protein concentration and in fact increases for higher concentrations of protein. Chemicals for which this behavior has been seen include bromosulphophthalein (BSP), oleate, and indocyanine green (Weisiger et al, 1984;Ockner et al, 1983; and Ott and Weisiger, 1997).Previous related studies have focused on the BSP uptake rate for exposure of the elasmobranch liver to a fixed, unvarying concentration of chemical in a single pass perfiision system (Weisiger et al, 1984) or on the 1 st pass extraction fraction (Goresky, 1964;Gumucio et al, 1984;Orzes et al, 1985). The study presented here examined the effect of non-equilibrium binding between bovine serum albumin (hereafter referred to as albumin) and BSP on the uptake of BSP by the rat liver, which like other mammalian livers has a much greater BSP uptake rate than the elasmobranch liver.…”