Figure 4

The rate of the fusion pore opening is slowed in syt I knockdown cells that overexpress syt IV, but neither the amplitude nor quantal content of the individual release events are altered following syt IV upregulation. The 'double' means of the amplitude (A) and quantal content (B) values are shown in bar histograms for forskolin-treated and untreated control, shRNA-syt I knockdown, and CT cells. (C) The mean rate of rise (pA/ms) for each group of cells is plotted for the control and shRNA-syt I knockdown cells with control, endogenous levels of syt IV expressed, upregulated syt IV expression by forskolin treatment, or overexpression of syt IV by transfection with pSyt IV (*p < 0.05, **p < 0.01).