Saxitoxin and tetrodotoxin: comparison of nerve blocking mechanism.

Saxitoxin at concentrations of 3 x 10(-8) to 3 x 10(-7) mole per liter blocks the conduction of lobster giant axon with no change in resting potential. Recovery of washed axons is faster in those that had been treated with saxitoxin than it is in those that were treated with tetrodotoxin. Peak transient increase in nerve membrane conductance is selectively blocked by saxitoxin with no change in late steady-state increase in conductance. The major mechanism of saxitoxin blockage is the same that of tetrodotoxin blockage.