The binding of tritiated tetrodotoxin to squid giant axons.

The binding of tetrodotoxin to squid gian axons was determined as a function of toxin concentration, using a tritiated toxin preparation of known radiochemical purity and specific activity. From the amount of saturable binding observed, the number of toxin binding sites thought to be sodium channels was found to be 553 plus or minus 119/mum-2 of axon surface.