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ID naloge: 82 Letnik: 2000 Predmet: farmakologija
Vpletenost endotelija pri ucinkih ekvinatoksina II na izolirano prašicjo koronarno arterijo
Avtor: Simona Kirbiš
Mentor: prof.dr. Metka V. Budihna, dr.med
Somentor: dr. Matjaž Bunc, dr. med., mag. Gorazd Drevenšek,dipl.biol.
Izhodišce: Ekvinatoksin II (EqT II) je bazicen protein, s toksicnim delovanjem, izoliran iz morske vetrnice Actinia equina (L.) in sodi v skupino aktinoporinov. Vzrok smrti poskusnih živali so ucinki toksina na kardiorespiratorni sistem. Pomen neposrednih kardiotoksicnih ucinkov toksina in mehanizem zmanjšanja koronarnega pretoka pa je ostal nepojasnjen.
Namen dela in hipoteze: V pricujoci raziskavi smo želeli pojasniti mehanizem skrcenja obrocka izolirane koronarne žile prašica po dodatku EqT II. Želeli smo preveriti: 1) ali se pod vplivom EqT II iz endotelija koronarne žile sprošca endotelin-1 (ET-1), ki povzroci skrcenje gladke mišicne celice v žilni steni in 2) ali lahko s pomocjo tezosentana, ki je eksperimentalni zaviralec endotelinskih receptorjev ETA in ETB (oboji so receptorji za ET-1), kompetitivno zavremo ucinek ET-1 tudi na izolirani prašicji koronarni arteriji.
Metode: Krcenje obrockov izolirane prašicje koronarne arterije smo merili z mehansko-elektricnim pretvornikom. Krcenje izoliranih obrockov po dodatku EqT II smo primerjali z ucinkom 30 mM KCl na istih izoliranih obrockih koronarnega žilja in jih izrazili kot relativne vrednosti. Rezultate smo izrazili kot srednjo vrednost ± standardno napako ocene povprecij (x ± SEM).
Rezultati: Ekvinatoksin II je povzrocil od koncentracije odvisno krcenje izolirane koronarne arterije z ohranjenim endotelijem. Pri mehansko odstranjenem endoteliju EqT II ni povzrocil merljivega krcenja izolirane koronarne arterije. Tezosentan v koncentraciji 1 µmol/l je za vec kot 60% zmanjšal skrcenje prašicje koronarke pod vplivom EqT II.
Zakljucki: Naši poskusi kažejo na to, da je skrcenje obrockov koronarnega žilja po dodatku EqT II posledica sprošcanja ET-1, saj je tezosentan, ki je nespecificen zaviralec receptorjev ETA in ETB, v veliki meri zmanjšal skrcenje po dodatku EqT II.
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[Abstract / English version]
Involvement of endothelium in effects of equinatoxin II in isolated porcine coronary artery
Author: Simona Kirbiš
Mentor: prof.dr. Metka V. Budihna, dr.med
Co-mentor: dr. Matjaž Bunc, dr. med., mag. Gorazd Drevenšek,dipl.biol.
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 1µM 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.
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