Characterisation of zinc uptake and its regulation by arachidonic
acid in fetal type ii pneumocytes.
Ong, T. J., P. J. Kemp, R. E. Olver, and H. J. McArdle.
Centre for Research into Human Development, University of Dundee,
Department of Child Health, Ninewells Hospital and Medical School,
Dundee, DD1 9SY, UK., Tel # (+44) (382) 60111 XT 3308 or 2179, Fax #
(+44) (382) 645783, e-mail H.J.McArdle@dundee.ac.uk
APStracts 2:0043L, 1995.
In freshly isolated fetal guinea pig type II pneumocytes, zinc uptake
is time- and temperature-dependent. Two pathways of uptake exist,
resulting in a rapid phase which reaches a steady state within 30 s,
and a slower linear phase which does not attain a steady state within
60 min. Both processes exhibit saturation kinetics. The rapid phase
has a maximal zinc uptake of 60.7 +/- 9.3 pmol. (106 cells)-1 in 30 s
and a Kt (apparent affinity) of 13.7 +/- 5.4 [mu]M. The maximum
velocity of uptake (Vmax) of the slower phase is 24.6 +/- 1.9 pmol.
(106 cells)-1. min-1 with a Kt of 22.0 +/- 3.6 [mu]M. Epinephrine,
terbutaline, dibutyryl cAMP and dexamethasone have no significant
effect on zinc uptake, while arachidonic acid (AA) stimulates. Dose
-response data of AA-stimulated zinc uptake gives an apparent K0.5 of
0.42 +/- 0.01 [mu]M and a Hill coefficient of 1. The maximal uptake
in the rapid phase is significantly increased to 146.8 +/- 12.4 pmol.
(106 cells)-1 in 30 s and in the slow phase, the Vmax for Zn uptake
is also significantly increased to 33.0 +/- 1.8 pmol. (106 cells)-1.
min-1 by 10 [mu]M AA However, the Kt values in both processes remains
unchanged after AA stimulation. The effect is not mediated by either
leukotrienes or prostaglandins but can be mimicked by other
unsaturated fatty acids.
Received 31 October 1994; accepted in final form 15 March 1995.
APS Manuscript Number L313-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.