PT  - JOURNAL ARTICLE
AU  - Kirk E. Dineley
AU  - Latha M. Malaiyandi
AU  - Ian J. Reynolds
TI  - A Reevaluation of Neuronal Zinc Measurements: Artifacts Associated with High Intracellular Dye Concentration
AID  - 10.1124/mol.62.3.618
DP  - 2002 Sep 01
TA  - Molecular Pharmacology
PG  - 618--627
VI  - 62
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/62/3/618.short
4100  - http://molpharm.aspetjournals.org/content/62/3/618.full
SO  - Mol Pharmacol2002 Sep 01; 62
AB  - The emergence of zinc as a potent neurotoxin has prompted the development of techniques suitable for the measurement of intracellular free zinc ([Zn2+]i) in cultured cells. Accordingly, a new family of Zn2+-sensitive fluorophores has become available. Using ionophore-induced elevations of [Zn2+]i in cultured neurons, we measured [Zn2+]i-induced changes in the novel dyes FuraZin-1 and FluoZin-2 and compared them with the established [Zn2+]i-sensitive fluorophores mag-fura-2 and Newport Green. All of these dyes effectively detected [Zn2+]i, and FuraZin-1, FluoZin-2, and Newport Green showed selectivity for [Zn2+]iover [Ca2+]i and [Mg2+]i. However, the dyes showed little difference in their apparent sensitivity to [Zn2+]i, even though their in vitro affinities for Zn2+ varied from 20 nM to 3 μM. We show herein that this is a consequence of the relatively high concentrations of intracellular dye used in experiments of this nature. Thus, for the measurement of [Zn2+]i, the sensitivity of the reporting system is dominated by the intracellular dye concentration, whereas dye affinity is unimportant. We extend these findings to show that calibration of dye signal to ion concentration is critically dependent on precise measurement of intracellular dye concentration.