![cubed root of catecholamine released. Plots of the percent of total events observed in the first 40 s following initiation of release vs. the cubed root of the amount of catecholamine released upon elevated potassium stimulation for (A) 17 undifferentiated PC12 cells (475 total release events) and (B) 16 differentiated PC12 cells (156 total release events). (Reproduced from Brain Res. with permission [3].)](https://images.tandf.co.uk/common/jackets/crclarge/978082470/9780824707316.jpg "cubed root of catecholamine released. Plots of the percent of total events observed in the first 40 s following initiation of release vs. the cubed root of the amount of catecholamine released upon elevated potassium stimulation for (A) 17 undifferentiated PC12 cells (475 total release events) and (B) 16 differentiated PC12 cells (156 total release events). (Reproduced from Brain Res. with permission [3].)")
ABSTRACT
PC12 cells have been cotransfected with either a BoNT/C1-encoding plasmid or a control pcDNA3 plasmid, together with a plasmid encoding enhanced green fluorescent protein, EGFP [5]. This allows transfected cells to be identified for subsequent quantitative amperometric measurements of individual catecholamine release events. Four to six days after transfection, the cells are loaded with dopamine prior to the experiments to enhance the amperometric signal, and the ATP-elicited amperometric responses from cells under three different conditions are compared. Nontransfected cells that have undergone the transfection protocol but do not express EGFP show qualitatively similar responses to those of normal control cells. EGFP-expressing cells that are cotransfected with the control pcDNA3 plasmid in the absence of the toxin pBoNT/C1 also exhibit responses similar to those of control cells, thus indicating that the expression of EGFP alone has little or no effect on the response to ATP in terms of spike amplitude or frequency. In contrast, however, the response to ATP stimulation is dramatically altered for fluorescent cells from dishes cotransfected with pEGFP and pBoNT/C1 (Figure 20).
