AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 5 707-G713, Copyright © 1990 by American Physiological Society
Effect of colchicine on the clearance of ferritin in vivo
G. A. Ramm, L. W. Powell and J. W. Halliday
Department of Medicine, University of Queensland, Royal Brisbane Hospital, Australia.
The effect of the microtubular inhibitor colchicine, administered at either
0.036 (dose 1) or 5 mumol/kg (dose 2), on hepatic ferritin uptake was
determined over a 5-h period of ferritin infusion in normal and iron-loaded
rats. In the absence of colchicine, the serum ferritin concentration of
normal rats was reduced after 5 h to 20 +/- 9% and in iron-loaded rats to
30 +/- 1% of the expected values, indicating ferritin clearance. After
colchicine (dose 1), a similar result was observed in normal rats; however,
in iron-loaded rats, an increase in serum ferritin to 77 +/- 16% of the
expected value indicated a decreased ferritin clearance and/or increased
ferritin release. The administration of the higher dose to normal rats also
resulted in an increase in serum ferritin to 72 +/- 2% of the expected
value. In iron-loaded rats, after dose 2 the ferritin concentration rose to
359 +/- 108% of the expected value, consistent with the release of
endogenous ferritin. Colchicine administration had no effect on biliary
ferritin in normal rats; however, in iron-loaded rats, both doses resulted
in a fivefold increase in the release of biliary ferritin. The results
suggest that ferritin uptake is facilitated by receptor-mediated
endocytosis, which is partially inhibited by colchicine. Release of
ferritin also occurs as a result of colchicine administration, and this is
dependent on both the dose of colchicine and the iron status of the animal.
