Author/Editor		Bunc, Matjaž
Title		Učinki equinatoxina na gladko mišico koronarne arterije - možni vzroki kardiotoksičnosti
Type		monografija
Place		Ljubljana
Publisher		Univerza v Ljubljani, Medicinska fakulteta
Publication year		1992
Volume		str. 46
Language		slo
Abstract		Equinatoxin II is a highly lethal protein isolated from the tentacles of the sea anemone Actinia equina (L.). The following study describes the effects of Equinatoxin II in vivo on experimental animals (Wistar rat) and in vitro on freshly isolated coronary arteries taken from pig. Rats received 3 LD50 of Equinatoxin II intravenously and ECG as well as respiratory activity were recorded. The immediate effects of the application of the toxin were severe arrhythmia and cessation of respiration. Hematocrit was reduced and the concentration of potassium ions increased several fold, which implies intravascular hemolysis. This is probably the main reason for the observed effects, although several findings suggest that other effects are significantly contributing to the toxicity of Equinatoxin II. The fact that the hemolytic activity of other isotoxins from the same sea anemone is inversely proportional to their hemolytic activity is in accordance with this view. Perfusion of hearts from several vertebrates results in an abrupt decrease of the coronary perfusion, which suggests coronary vasoconstriction. This is most probably another adequate explanation for the cardiotoxicity of this toxin. However, our study of the effects on the isolated coronary arteries of the Equinatoxin II shows clearly that the toxin has no effect on coronary arteries with large diameter. This finding was independent of the presence of endothelium on the blood vessels. As the dramatic reduction of the rate of the perfusion of isolated heart has been proven by several authors we propose another explanation of this phenomenon. Most probably the toxin selectively affects smooth muscle cells in small blood vessels, possibly in precapillary sphincters. Nevertheless, hyperkalemia remains the other important component of the cardiotoxicity of Equinatoxin II.
Descriptors		CORONARY VESSELS CNIDARIAN VENOMS ARRHYTHMIA RESPIRATORY INSUFFICIENCY HYPERCALCEMIA RATS, WISTAR SEA ANEMONES SWINE ELECTROCARDIOGRAPHY