[Effect of tetanus toxin on K+ and Na+ concentration in synaptosomes]

A study was made of the effect of tetanus toxin (TT) in doses of 20-1000 MLD (for rats) on synaptosomes isolated from the rat brain cortex. TT produced a decrease in K+ content in synaptosomes. The effect depended on the dose of TT (I50=22 MLD). The content of Na+ remained unchanged. The action of TT depended on the time and the maximal effect was seen upon 60 minutes of incubation. TT inactivated by boiling or by antitoxin did not affect K+ content in synaptosomes. An increase of K+ concentration up to 17 mM in an incubation medium led to an increase in K+ content in TT-poisoned synaptosomes but not in the control ones. Possible changes in membrane electrogenesis in nerve terminals caused by TT are discussed.