The importance of hemolysis in the lethal effects of equnatoxin II, a protein from the sea anemone Actinia equina (L.)

Equinatoxin II (EqT II) is one of the three isotoxins isolated from the sea anemone Actinia equina (L). The cause of death due to i.v. application of Eq T II was attributed to its hemolytic activity and hiperkaliemia, and the direct cardio-respiratory effects of the toxin. The toxin also binds to plasma lipids and forms toxic conglomerates with them. In our study we tried to evaluate the importance of interaction of the toxin with blood components in the toxin lethality. Anaesthetized male Wistar rats were used. The respiratory activity, ECG and animal serum ionic composition were monitored. To simulate isolated effects of the toxin hemolytic activity, hemolysed erythrocytes, KCl and mixture of rat serum with the toxin were injected i.v.. It was shown that neither the lysed erythrocytes nor the mixture of rat serum with the toxin were lethal for the experimental animals. Even KCl, in concentrations detected in serum of rats killed by the toxin, did not cause the death of experimental animals. Our results indicate that either a combination of the tested effects of the toxin on blood components or more probably the direct effects of the toxin on vital organs are responsible for the toxin lethality.