title: Effects induced by Tityus serrulatus scorpion venom and its toxins TsTX-I and TsTX-V on the rat isolated retractor penis muscle.
abstract: The aims of the present study were to investigate the pharmacological effects induced by Tityus serrulatus venom (TsV) and its fractions and to compare with the effects induced by pure alpha (TsTX-V) and beta (TsTX-I) toxins isolated from TsV on rat retractor penis muscle (RPM). TsV, fractions X, XI, XIIa, XIIb (0.01-100 microg/ml) and TsTX-V (1 nmol/l-10 micromol/l) induced concentration-dependent contractions. Prazosin and guanethidine or tetrodotoxin (TTX, 5 micromol/l, 30 min) completely abolished these contractions, suggesting complete dependence on sympathetic nerves. TsV or fractions X, XI, XIIa, XIIb (0.01- 100 microg/ml), TsTX-I and TsTX-V (1 nmol/l-10 micromol/l) induced concentration-dependent relaxations in the precontracted RPM. TTX or N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 micromol/l, 30 min) completely abolished the relaxations. Our results suggest that most of TsV-derivated toxins induce contraction and relaxation on RPM by sympathetic and NANC nitrergic nerve stimulation. Noteworthy, TsTX-I only induces relaxation on RPM suggesting that this protein selectively acts on inhibitory nerves.
authors.affiliation: Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Brasil.
authors.forename: José Henrique G G
authors.initials: JH
authors.lastname: Bomfim
authors.forename: Márcio A F
authors.initials: MA
authors.lastname: de Godoy
authors.forename: José R
authors.initials: JR
authors.lastname: Giglio
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: de Oliveira
authors.forename: Eliane C
authors.initials: EC
authors.lastname: Arantes
mesh_terms: D000818:Animals; D018723:Bethanechol / Q000494:pharmacology; D001681:Biological Assay / Q000379:methods; D005591:Chemical Fractionation / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004305:Dose-Response Relationship, Drug; D006145:Guanethidine / Q000494:pharmacology; D019476:Insect Proteins; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009498:Neurotoxins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D010108:Oxyhemoglobins / Q000494:pharmacology; D010413:Penis / Q000033:anatomy & histology / Q000187:drug effects / Q000473:pathology*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D012604:Scorpion Venoms / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D012605:Scorpions; D020539:Sequence Analysis, Protein; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D019476:Insect Proteins; D009498:Neurotoxins; D010108:Oxyhemoglobins; D012604:Scorpion Venoms; C093405:scorpion toxin CsE-V; C120263:scorpion toxin Ts1, Tityus; C033843:toxin V; D018723:Bethanechol; D013779:Tetrodotoxin; D019331:NG-Nitroarginine Methyl Ester; D011224:Prazosin; D006145:Guanethidine