Fig. 7. Muscle stimulation prevents loss of recycled AChRs from denervated NMJs. Three days after labeling with BTX-biotin/strept-488, recycled AChRs on denervated muscle were labeled with strept-594 and imaged immediately, and then again after 8 hours in the absence (A) and presence (B) of stimulation. Scale bar, 20 µm. (C) Graph summarizing the fluorescence measurements obtained from many synapses. After 8 hours, 66% of fluorescence from recycled receptors remained in denervated synapses; however, when denervated muscle was chronically stimulated, this loss of fluorescence was largely abolished.