title: Changes in sensitivity of the isolated guinea-pig vas deferens induced by a lyophilized Phoradendron latifolium leaf infusion.
abstract: The effect of a lyophilized mistletoe infusion (LMI) was studied on isolated guinea-pig vas deferens. LMI caused a contraction which was partially blocked by phentolamine but not by atropine. LMI caused a shift to the left of the norepinephrine concentration-effect curve (CEC), an effect which appeared to be blocked by atropine and was absent in animals previously treated with reserpine and alpha-methyl-para-tyrosine. The increase of the norepinephrine maximal response induced by LMI was not blocked by atropine or pharmacological denervation. LMI caused a shift to the right of the acetylcholine CEC and had no effect on the acetylcholine maximal response. These results suggest that the effects seem to be due mainly to the presence of potassium ion in the LMI; however, the participation of muscarinic agonist(s) of reduced intrinsic activity or some tyramine-like substance could not be ruled out.
authors.affiliation: Departamento de Morfologia e Fisiologia Animal, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, São Paulo, Brazil.
authors.forename: A
authors.initials: A
authors.lastname: Queiroz-Neto
authors.forename: I
authors.initials: I
authors.lastname: Melito
mesh_terms: D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005612:Freeze Drying; D006168:Guinea Pigs; D008297:Male; D014784:Mistletoe; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000502:physiology; D010646:Phentolamine / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal; D011188:Potassium / Q000032:analysis; D013053:Spectrophotometry; D014649:Vas Deferens / Q000187:drug effects* / Q000294:innervation
chemical_list: D010936:Plant Extracts; D001285:Atropine; D000109:Acetylcholine; D011188:Potassium; D009638:Norepinephrine; D010646:Phentolamine