AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 6 760-G764, Copyright © 1986 by American Physiological Society
Distribution of epidermal growth factor binding sites in the adult rat liver
J. G. Chabot, P. Walker and G. Pelletier
The localization of epidermal growth factor (EGF) receptors was studied in
the liver by use of light microscope autoradiography performed at different
time intervals (2-60 min) after intravenous injection of 125I-EGF into
adult rat. The results revealed a substantial binding of EGF to parenchymal
cells of the liver. Control experiments indicated that the autoradiographic
labeling was due to specific interaction of 125I-EGF with its receptor. A
very steep portal-to-central lobular concentration gradient for 125I-EGF
uptake was observed. The time course study performed on parenchymal cells
of periportal regions of lobules showed that, at the 2-min time interval,
most silver grains were found at the periphery of these cells and that the
maximal values were reached 7 min after injection. After, the number of
grains decreased progressively and their localization in the cytoplasm
indicated the internalization of the ligand. The present results
demonstrate that EGF injected into the general circulation preferentially
binds to hepatocytes located in the periportal area and is rapidly
internalized.
