Fluorescent staining of neuromuscular junctions by using the antibody against acetylcholine receptors of Narke japonica, and double staining with the antibody and erabutoxin b.

The neuromuscular junctions of various vertebrates were visualized by indirect immunofluorescence microscopy using antibody against purified acetylcholine receptors (AChRs) of the electric organ from Narke japonica. Further, by using rhodamine-labeled erabutoxin b (TMR-Eb), we showed that AChRs at the neuromuscular junctions of frog, chick and mouse muscle could not be doubly stained with the antibody and erabutoxin b. AChRs of snake muscle could not be stained with TMR-Eb, while they were stained with the antibody against AChR. Moreover, the antibody did not inhibit the binding of 3H-labeled erabutoxin b to the solubilized AChRs from the mouse muscle. These results indicate that, as far as the antibodies against Narke AChRs are concerned, most antibody-binding sites in the molecules of muscle AChR in situ are different from those responsible for binding of the snake neurotoxin.