Tetrodotoxin binding to normal depolarized frog muscle and the conductance of a single sodium channel.

摘要: 1. We have examined the binding of tritium-labelled and unlabelled tetrodotoxin to frog twitch muscle. Bio-assay as well radioisotope experiments show a saturable component with capacity about 22 p-mole/g wet wt., dissociation constant 5 nM. 2. If observed uptake by muscles represents one-to-one drug sodium channels, channel density is 380 channels/mum2 muscle fibre's surface membrane. On basis this result electrical measurements conductance in muscle, we calculate that single order 10(-12) reciprocal ohms. This one two orders magnitude less than previous estimates. 3. looked for an effect membrane depolarization on binding, found none. suggests there little molecular interaction between "gating" portion molecule, which binds tetrodotoxin.