Distribution of Ca2+ channels on frog motor nerve terminals revealed by fluorescent omega-conotoxin.

摘要: Tetramethylrhodamine-conjugated omega-conotoxin was used as a fluorescent stain (Jones et al., 1989) to determine the spatial distribution of voltage-gated Ca2+ channels along frog motor nerve terminals. Like native omega-conotoxin, toxin blocked neuromuscular transmission irreversibly. The staining confined junction and consisted series narrow bands (in face views) or dots side approximately 1 micron apart. This characteristic pattern prevented by pretreatment with prior denervation for 5–7 d. Combined fluorescence phase-contrast optics indicated that on synaptic rather than nonsynaptic terminal. proved be in register postsynaptic junctional folds, revealed combined ACh receptors. It is concluded terminals are concentrated at active zones. findings consistent suggestion (Heuser 1974; Pumplin 1981) large intramembraneous particles seen freeze-fractured zones channels.