The acetylcholine receptors of human muscles are not stained with rhodamine-labeled erabutoxin-b.

The skeletal muscles from man and other vertebrates were incubated in rhodamine-labeled erabutoxin-b(TMR-Eb), and the distribution of the acetylcholine receptors (AChRs) at the neuromuscular junctions was examined under a fluorescence microscope. The AChRs of human muscles were not stained with TMR-Eb, whereas those of fish, frog, chicken, mouse, rat, cat and monkey muscles were stained under the same conditions. It was concluded that human AChRs have low or no binding ability for TMR-Eb.