title: Cardiovascular effects of Sp-CTx, a cytolysin from the scorpionfish (Scorpaena plumieri) venom.
abstract: Fish venom cytolysins are multifunctional proteins that in addition to their cytolytic/hemolytic effects display neurotoxic, cardiotoxic and inflammatory activities, being described as "protein lethal factors". A pore-forming cytolysin called Sp-CTx (Scorpaena plumieriCytolytic Toxin) has been recently purified from the venom of the scorpionfish Scorpaena plumieri. It is a glycoprotein with dimeric constitution, comprising subunits of approximately 65 kDa. Previous studies have revealed that this toxin has a vasorelaxant activity that appears to involve the L-arginine-nitric oxide synthase pathway; however its cardiovascular effects have not been fully comprehended. The present study examined the cardiovascular effects of Sp-CTx in vivo and in vitro. In anesthetized rats Sp-CTx (70 μg/kg i.v) produced a biphasic response which consisted of an initial systolic and diastolic pressure increase followed by a sustained decrease of these parameters and the heart rate. In isolated rats hearts Sp-CTx (10(-9) to 5 × 10(-6) M) produced concentration-dependent and transient ventricular positive inotropic effect and vasoconstriction response on coronary bed. In papillary muscle, Sp-CTx (10(-7) M) also produced an increase in contractile isometric force, which was attenuated by the catecholamine releasing agent tyramine (100 μM) and the β-adrenergic antagonist propranolol (10 μM). On isolated ventricular cardiomyocytes Sp-CTx (1 nM) increased the L-type Ca(2+) current density. The results show that Sp-CTx induces disorders in the cardiovascular system through increase of sarcolemmal calcium influx, which in turn is partially caused by the release of endogenous noradrenaline.
authors.affiliation: Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal do Espírito Santo, Vitória, ES, Brazil.
authors.forename: Helena L
authors.initials: HL
authors.lastname: Gomes
authors.affiliation: Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal do Espírito Santo, Vitória, ES, Brazil.
authors.forename: Thiago N
authors.initials: TN
authors.lastname: Menezes
authors.affiliation: Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal do Espírito Santo, Vitória, ES, Brazil.
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Malacarne
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Danilo
authors.initials: D
authors.lastname: Roman-Campos
authors.affiliation: Departamento de Educação, Universidade do Estado da Bahia, Guanambi, BA, Brazil.
authors.forename: Antonio N
authors.initials: AN
authors.lastname: Gondim
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Jader S
authors.initials: JS
authors.lastname: Cruz
authors.affiliation: Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal do Espírito Santo, Vitória, ES, Brazil.
authors.forename: Dalton V
authors.initials: DV
authors.lastname: Vassallo
authors.affiliation: Departamento de Ciências Fisiológicas, Centro de Ciências da Saúde, Universidade Federal do Espírito Santo, Vitória, ES, Brazil. Electronic address: suelygf@gmail.com.
authors.forename: Suely G
authors.initials: SG
authors.lastname: Figueiredo
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001938:Brazil; D054715:Cardiotoxins / Q000008:administration & dosage / Q000302:isolation & purification / Q000633:toxicity*; D002478:Cells, Cultured; D003326:Coronary Circulation / Q000187:drug effects*; D029941:Fish Proteins / Q000008:administration & dosage / Q000302:isolation & purification / Q000633:toxicity; D005397:Fish Venoms / Q000737:chemistry*; D006023:Glycoproteins / Q000008:administration & dosage / Q000302:isolation & purification / Q000633:toxicity; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D010473:Perciformes; D054353:Perforin / Q000008:administration & dosage / Q000302:isolation & purification / Q000633:toxicity*; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000302:isolation & purification / Q000633:toxicity
chemical_list: D054715:Cardiotoxins; D029941:Fish Proteins; D005397:Fish Venoms; D006023:Glycoproteins; D014662:Vasoconstrictor Agents; D054353:Perforin
keywords: Cardiotoxic; Cytolysin; Fish venom; Scorpaena plumieri