AJP - Gastrointestinal and Liver Physiology, Vol 246, Issue 1 86-G95, Copyright © 1984 by American Physiological Society
Albumin influences sulfobromophthalein transport by hepatocytes of each acinar zone
D. L. Gumucio, J. J. Gumucio, J. A. Wilson, C. Cutter, M. Krauss, R. Caldwell and E. Chen
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.
