Fig. 2. The pattern of immunofluorescence obtained using mAb 306 mimics the distribution of BgT-binding in submucosal ganglia, and the block of BgT-binding by nicotine confirms that BgT reacts specifically with enteric 7-nAChRs. (A) Submucosal ganglion stained with mAb 306 (17 nmol l^–1) and FITC-conjugated goat-anti-mouse. Fixed tissue permeabilized with Triton X-100 (0.5%). (B) Negative control for A, obtained from the same preparation in the absence of mAb 306. (C) Binding of Alexa 594-conjugated BgT (250 nmol l^–1) to a live segment of submucosal plexus. (D) The binding of Alexa 594-conjugated BgT was blocked by a 16 h co-incubation with 1 mmol l^–1 nicotine. Scale bar, 25 µm.