AJP - Heart and Circulatory Physiology, Vol 272, Issue 5 2095-H2106, Copyright © 1997 by American Physiological Society

ARTICLES

Oxidants increase intracellular free Zn2+ concentration in rabbit ventricular myocytes

B. Turan, H. Fliss and M. Desilets
Department of Biophysics, Faculty of Medicine, University of Ankara, Turkey.

Oxidative stress may alter cardiac function by affecting intracellular free Zn2+ concentrations ([Zn2+]i). Rabbit ventricular myocytes loaded with fura 2 were used to fluorometrically measure resting [Zn2+]i (0.23 +/- 0.03 nM) and intracellular Ca2+ concentration ([Ca2+]i) (36 +/- 7 nM). Fluorescence quenching by the heavy metal chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine was used to quantitate [Zn2+]i. The thiol-reactive oxidants hypochlorous acid (0.1 mM) and selenite (1 mM) increased [Zn2+]i to 7.7 +/- 1.7 and 6.1 +/- 1.7 nM, respectively, within 5 min. 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, it led to overestimation of [Ca2+]i by approximately twofold before oxidant treatment and by approximately eightfold after oxidants. The results demonstrate that [Zn2+]i 1) can be greatly increased by thiol-reactive oxidants; 2) may contribute to oxidant-induced alterations of excitation-contraction coupling; and 3) has strong fura 2 fluorescence which, if overlooked, can lead to significant overestimation of [Ca2+]i.

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