title: Effects of tyramine on the human uterine artery in vitro.
abstract: 1. We have studied the effects of tyramine on the human uterine artery (HUA) in order to assess its site of action. 2. Tyramine (5 x 10(-5) to 10(-3) M) contracts the isolated human uterine artery. Tachyphylaxis appeared when concentration-response curves were repeated and the contraction was diminished by prazosin (10(-8), 10(-7) and 10(-6) M). The maximal contraction induced by tyramine (10(-3) M) was 25% of the maximal response to noradrenaline (10(-5) M). 3. After 2 hr of tyramine perfusion a decrease of the contractile response to KCl, 30 and 60 mM (15.0 and 12.9%) and noradrenaline 10(-6) M (83.2%) is shown. 4. However, when tyramine was previously added for 3 min to the bath, the response to KCl increased while the response to noradrenaline was lower. 5. A possible postsynaptic antagonistic effect for tyramine in the HUA is suggested in addition to its usual presynaptic effect.
authors.affiliation: Facultad de Medicina, Departamento de Medicina, Oviedo, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Garcia de Boto
authors.forename: R
authors.initials: R
authors.lastname: Molina
authors.forename: F
authors.initials: F
authors.lastname: Andrés-Trelles
authors.forename: A
authors.initials: A
authors.lastname: Hidalgo
mesh_terms: D000818:Animals; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011817:Rabbits; D013618:Tachyphylaxis / Q000502:physiology; D014439:Tyramine / Q000494:pharmacology*
chemical_list: D011189:Potassium Chloride; D009638:Norepinephrine; D014439:Tyramine; D011224:Prazosin