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. Author manuscript; available in PMC: 2010 Apr 29.
Published in final edited form as: J Am Chem Soc. 2009 Apr 29;131(16):5760–5762. doi: 10.1021/ja900852k

Figure 3.

Figure 3

Sequestration of cholera toxin from cell culture media. The current (Isc) represents the net sum of the transepithelial anion and cation fluxes and reflects the level of ion and fluid secretion.13 Cell monolayers were pre-incubated with CT-containing media for 40 minutes at 37 °C before removing the media and beginning measurement of Isc at t=0. To eliminate the contribution of Ca2+- or ATP-activated chloride secretion, P2- and IP3-receptor antagonists (suramin and 2-APB) were used during recording. (-■-) Positive control: cells pre-incubated with CT (1 nM) in 1.5 ml of culture media. (-□-) Trial 1: CT (1 nM) in 1.5 ml of culture media was exposed to ~5000 CTLt-displaying beads. After 30 minutes, the media was removed from the beads and placed over the cells for the 40-minute pre-incubation period. (-Δ-) Trial 2: repeat of Trial 1. Arrows denote the addition of glibenclamide, a chloride-channel blocker. All currents were normalized to a negative control (current measured with no toxin) and experiments were run sequentially on the same apparatus.