Avtor/Urednik		Budihna, MV; Maček, P; Šuput, D
Naslov		Some possible mechanisms involved in the cardiotoxicity of equinatoxin II
Tip		članek
Vir		In: Gopalakrishnakone P, Tan CK, eds. Recent advances in toxinology research. Vol 2. Singapore: National university,
Leto izdaje		1992
Obseg		str. 402-7
Jezik		eng
Abstrakt		Equinatoxin II (EqT II) is a cardiotoxic 19 kDa polypeptide, isolated from the sea anemone Actinia equina L. To study its cardiotoxicity guinea pigs' hearts isolated according to Langendorff were used. Isolated hearts were perfused either by oxygenated Ringer Lnekc solution (12L) alcine or RL containing 10 micro M atropine or 0.1 micro M carbachol or 0.1 micro M ketanserin or 20 nM verapamil or 1.3 micro M nitroglycerin. Eqt II was dissolved in one ml of oxygenated RL, containing 0.1 per cent bovine serum albumin. It was injected into the perfusate above the aorta or directly into the left ventricle. EqT II in 1 pM to 1 micro M concentrations, injected above the aorta, diminished coronary flow, the force of ventricular contraction and the heart rate. ECG records revealed arrhythrnia. Effects of EqT II were dose dependent and showed striking tachyphylaxis. EqT II injected directly into the left ventricle in any of mentioned concentrations had no significant effect. Atropine and ketanserin did not influence the effects of EqT II. In the presence of carbachol all described effects of EqT II except arrhythmia were weaker and their onset was delayed. Verapamil and nitroglycerin abolished the negative inotropic effect of EqT II as well as reduction of coronary flow induced by the toxin. Verapamil prevented cardiac arrhythmias more efficiently than nitroglycerin. These results support the view that an increase in intracellular calcium concentration followed by vasospasm underlie the cardiotoxic effects of the toxin. However, some effects of low doses of EqT II are more probably mediated by changes of intracellular concentrations of second messengers. The observed tachyphylaxis as well as interactions with carbachol and nitroglycerin support this view.
Deskriptorji		HEART ARREST TOXINS VERAPAMIL NITROGLYCERIN GUINEA PIGS