Elimination rate of 65zinc as a measure of food intake: a
validation study in the mouse (mus sp).
McLean, J. A. and Speakman, J. R.
Department of Zoology, University of Aberdeen, Aberdeen, Scotland,
UK, AB9 2TN, Tel : 0224 272879, Fax : 0224 272396
APStracts 2:0242A, 1995.
We measured elimination of 65Zn in white mice (Mus musculus) using
daily whole body counting. Thirteen male mice were randomly divided
into three groups, each maintained at a different temperature. Each
animal was labelled with 65Zn on day 0 and monitored over days 0 to
48 post injection. Daily food intake and body masses of all the
animals were measured. We evaluated the ability of derived components
of the 65Zn elimination curves to predict food intake over different
phases of the measurement period. Food intake was significantly
different between temperature groups; temporal variation in food
intake was not inter-correlated between groups. Whole body
elimination of 65Zn involved a rapid decline over day 0 to day 1,
followed by a biexponential decline in counts over days 1 through 48.
Components of the first phase of the biexponential elimination curve
were not significantly related to food intake. The rate (k2) of
isotope elimination in the second phase was significantly related to
mean food intake over days 25 to 48, 13 to 24 and 37 to 48. Rate of
turnover in the second phase of elimination, incorporating the
variation in zinc body pool size (k2.1/N2), was the best predictor of
food intake, and accounted for 60% of the variability over day 37 to
48.
Received 15 June 1994; accepted in final form 2 May 1995.
APS Manuscript Number A591-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 June 1995.