Fig. 3.

Zn(II) secretion can be observed both in vivo and in vitro using the Zn(II)-responsive fluorescent probe, ZIMIR. (A) (Left) The two lipophilic chains on ZIMIR provide a mechanism for anchoring to the fluorescent agent to the extracellular surface of cells. (Right) In vivo experimental scheme showing placement of the microscope lens directly over the exposed prostate gland of a mouse after local administration of ZIMIR to the tissue. (B) In vivo confocal images of the prostate before (Left) and after (Right) i.p. injection of d-glucose. (C) In vitro fluorescence images of prostate epithelial cells (RWPE-1) grown in a low-glucose medium without (Left) or with (Right) 75 µM ZnSO₄. The cells were then removed from the culture medium and washed with buffer, and 1 μM ZIMIR was added to coat the outer surface of the cells to detect release of Zn(II) from intracellular stores. As shown, cells not incubated with ZnSO₄ did not release Zn(II) in response to glucose (Left), whereas cells that had accumulated substantial Zn(II) during incubation did release Zn(II) in response to glucose in a concentration-dependent manner.