Oxidants increase intracellular free zn2+ concentration in rabbit
ventricular myocytes.
Turan, Belma, Henry Fliss, and Michel D[acute]esilets.
Department of Biophysics, Faculty of Medicine, University of
Ankara, Ankara 06100, Turkey, and Department of Physiology, Faculty
of Medicine University of Ottawa, Ottawa K1H 8M5, Canada
APStracts 3:0536H, 1996.
Oxidative stress may alter cardiac function by affecting intracellular
free Zn2+ concentrations ([Zn2+]i). Rabbit ventricular myocytes
loaded with fura-2 to were used to fluorometrically measure resting
[Zn2+]i (0.23+/-0.03 nM) and [Ca2+]i (36+/-7 nM). Fluorescence
quenching by the heavy metal chelator TPEN was used to quantitate
[Zn2+]i. The thiol-reactive oxidants HOCl (0.1 mM) and selenite (1
mM) increased [Zn2+]i to 7.7+/-1.7 and 6.1+/-1.7 nM, respectively,
within 5 minutes. Dithiothreitol (0.5 mM), a disulfide reducing
agent, rapidly restored normal [Zn2+]i. The oxidants did not affect
[Ca2+]i. However, depolarization-induced Ca2+ transients and Ca2+
currents were zinc-dependent. [Zn2+]i-associated fluorescence was
substantial and, if ignored, led to overestimation of [Ca2+]i by
nearly equal to 2-fold before oxidant treatment, and by nearly equal
to 8-fold after oxidants. The results demonstrate that [Zn2+]i: i)
can be greatly increased by thiol-reactive oxidants; ii) may
contribute to oxidant-induced alterations of excitation-contraction
coupling, and iii) has strong fura-2 fluorescence which, if
overlooked, can lead to significant overestimation of [Ca2+]i.
Received 20 February 1996; accepted in final form 2 December
1996.
APS Manuscript Number H167-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996