Author/Editor		Kirbiš, Simona
Title		Vpletenost endotelija pri učinkih ekvinatoksina II na izolirano prašičjo koronarno arterijo
Type		monografija
Place		Ljubljana
Publisher		Medicinska fakulteta
Publication year		2000
Volume		str. 27
Language		slo
Abstract		Background: Equinatoxin II (EqT II) is a lethal basic protein isolated from the sea anemone Actinia equina (L.) and acts as actinoporin. The putative cause of death in experimental animals is cardiorespiratory arrest. The principal reason of the cardiotoxic effects of the toxin and the mechanism of reduction of coronary flow after the application of EqT II is poorly understood. Objective and hypothesis: In the present study we investigated the effects of EqT II on the isolated porcine left anterior descending coronary artery. We tried to confirm the hypothesis: 1) EqT II releases from endothelial cells endothelin-1 (ET-1) that mediates vasoconstriction, and 2) Tezosentan, an experimental nonspecific ETA and ETB (both are ET-1 receptors) endothelin receptor antagonist, competitively antagonises effects of ET-1 also in porcine coronary artery. Methods: Contractions were measured with mechanical-electrical transducer. We compared the contraction induced by EqT II with the contraction of 30 mM KCl in the same isolated ring of coronary artery and expressed it as the relative value. Results were expressed as mean +- standard error of the mean. Results: Equinatoxin II dose dependently contracted isolated coronary artery with intact endothelium. In arteries with removed endothelium EqT II did not cause measurable contractions of the isolated artery. Addition of the endothelin receptor antagonist tezosentan in 1 micro M concentration reduced the contraction of porcine coronary artery induced by EqT II for more than 60%. Conclusions: As in our experiments the endothelin receptor antagonist tezosentan significantly reduced the contraction of porcine coronary artery induced by EqT II, these results allow the conclusion that ET-1 mediates the vasoconstriction induced by EqT II.
Descriptors		CORONARY VESSELS ENDOTHELIUM, VASCULAR CNIDARIAN VENOMS SWINE CORONARY VASOSPASM SEA ANEMONES ENDOTHELINS RECEPTORS, ENDOTHELIN