Imaging synaptic zinc: promises and perils.
It is well established that some excitatory nerve terminals have high concentrations of Zn(2+) in their synaptic vesicles. For some time, it has been believed that synaptic Zn(2+) is released during neurotransmission and acts as a neuromodulator. Fluorescent Zn(2+) indicators that do not penetrate membranes offer the prospect of rendering the release of Zn(2+) visible. Here, I take a critical look at fluorimetric imaging experiments devised to determine whether Zn(2+) is released and show that they are particularly susceptible to artifacts. Moreover, I will argue that recent experiments suggest that, rather than being released, Zn(2+) is presented to the extracellular space firmly coordinated to presynaptic macromolecules.
Kay
Alan R
AR
Department of Biological Sciences, 336 BB, University of Iowa, Iowa City, IA 52242, USA. alan-kay@uiowa.edu
D000818:Animals; D016477:Artifacts; D005456:Fluorescent Dyes / Q000737:chemistry / Q000494:pharmacology; D005470:Fluorometry / Q000379:methods* / Q000592:standards; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry* / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013572:Synaptic Vesicles / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000032:analysis* / Q000378:metabolism
D005456:Fluorescent Dyes; D015032:Zinc