AJP - Gastrointestinal and Liver Physiology, Vol 272, Issue 6 1400-G1407, Copyright © 1997 by American Physiological Society
Characterization of intracellular copper pools in rat hepatocytes using the chelator diamsar
M. J. Bingham, A. M. Sargeson and H. J. McArdle
Department of Child Health, Ninewells Hospital and Medical School, University of Dundee, United Kingdom.
When hepatocytes are incubated with the chelator diamsar, two pools can be
identified, which we have termed extractable and nonextractable. On
entering the hepatocyte, 67Cu first associates with the extractable pool
and, after approximately 2 h, moves to the nonextractable pool. Both pools
demonstrate saturation and are filled as a function of Cu concentration and
incubation time. Using the Michaelis-Menten equation, we have estimated the
size of the pools after incubation with 67Cu for 30 min and 4 h. During
this period the extractable pool decreases in size from 200 +/- 27 to 116
+/- 5 pmol/microgram DNA, whereas the nonextractable pool increases from 28
+/- 9 to 77 +/- 11 pmol/microgram DNA. Movement of Cu from the
nonextractable pool to the extractable pool is slow and incomplete. Using
[3H]diamsar, we demonstrate that uptake of the chelator is not rate
limiting and probably does not occur by pinocytosis. Incubation with
diamsar does not affect the activity of superoxide dismutase or
cytochrome-c oxidase, although it does prevent the incorporation of 67Cu
into ceruloplasmin. Incubation with zinc, which induces metallothionein,
results in an increase in 67Cu associated with the nonextractable pool,
suggesting that 67Cu-metallothionein constitutes at least part of the
nonextractable pool.
