AJP - Gastrointestinal and Liver Physiology, Vol 266, Issue 2 282-G291, Copyright © 1994 by American Physiological Society
Plasma membrane order parameter in periportal and perivenular hepatocytes isolated from ethanol-treated rats
A. Benedetti, A. Tangorra, G. Svegliati Baroni, G. Ferretti, L. Marucci, M. Jezequel and F. Orlandi
Department of Gastroenterology, University of Ancona, Italy.
Hepatic ethanol (EtOH) metabolism has been assumed to involve hepatocytes
differently, according to their location in the hepatic acinus. This
study's aim was to gain information on plasma membrane (PM) order parameter
in periportal (PP) and perivenular (PV) hepatocyte-enriched fractions
isolated by a digitonin-collagenase perfusion technique from rats pair-fed
for 6-8 wk liquid diets containing either EtOH or isocaloric carbohydrates.
Fluorescence polarization (P) studies have been performed to measure PM
order parameter of PP and PV hepatocytes cultured for 2-6 h on glass cover
slips and labeled with
1-[4-(trimethylamino)phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), a
specific probe for PM of living cells. Fluorescence polarization and
microscopy indicated that TMA-DPH is a suitable probe to study PM order
parameter in subconfluent rat hepatocyte monolayers where it labeled, after
a rapid incorporation, PM of cells. In pair-fed control rats, PM order
parameter was lower in PP hepatocytes than in PV cells (P = 0.366 +/- 0.013
vs. 0.381 +/- 0.021, respectively, P < 0.02; n = 7). In EtOH-treated
rats, these zonal differences tended to disappear (P = 0.419 +/- 0.012 in
PP cells vs. 0.417 +/- 0.007 in PV cells; n = 7). In addition, the order
parameter was significantly higher either in PP or PV hepatocytes compared
with pair-fed control animals (P < 0.002 and 0.003, respectively). A
30-min culture of cells in the presence of 40-200 mM EtOH significantly
decreased the PM order parameter of hepatocytes isolated from pair-fed
control rats with respect to EtOH-treated animals both in PP and PV cells
(P < 0.01 and 0.02, respectively; n = 4).(ABSTRACT TRUNCATED AT 250
WORDS)
