title: Determining zinc with commonly used calcium and zinc fluorescent indicators, a question on calcium signals.
abstract: Investigations into the roles of Ca(2+) and Zn(2+) in cell biology have been facilitated by the development of sensitive fluorometric probes that have enabled the measurement of Ca(2+) or Zn(2+) in both extracellular and intracellular environments. It is critical to be aware of the specificity and relative selectivity of a probe for the targeted ion. Here, we investigated metal-ion responses by screening nominally Zn(2+)- or Ca(2+)-selective fluorophores in solutions containing various concentrations of Ca(2+), as a potential interferent for Zn(2+), or Zn(2+), as a potential interferent for Ca(2+). The results suggested that Zn(2+)-sensitive dyes were more specific for their targeted ion than dyes that targeted Ca(2+). Ca(2+)-sensitive dyes such as Calcium Green-1, Fura-2, and Fluo-3 showed a wide range of interaction with Zn(2+), even responding to Zn(2+) in the presence of high concentrations of Ca(2+). We demonstrate that these Ca(2+) indicators can effectively measure dynamic changes of cytosolic Zn(2+). Our results appeal for a new generation of Ca(2+) fluorophores that are more specific for Ca(2+) over Zn(2+). One implication of these results is that data obtained using Ca(2+)-sensitive dyes may need to be re-examined to determine if results previously attributed to Ca(2+) could, in part, be due to Zn(2+).
authors.affiliation: Department of Biomedical Sciences, Program in Molecular and Cellular Biology, Ohio University, Athens, OH 45701, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Martin
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Stork
authors.forename: Yang V
authors.initials: YV
authors.lastname: Li
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis*; D002614:Chelating Agents / Q000737:chemistry*; D005069:Evaluation Studies as Topic; D005456:Fluorescent Dyes / Q000737:chemistry*; D006624:Hippocampus / Q000737:chemistry; D008297:Male; D008422:Materials Testing; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D015032:Zinc / Q000032:analysis*
chemical_list: D002614:Chelating Agents; D005456:Fluorescent Dyes; D015032:Zinc; D002118:Calcium