title: Dual effects of histamine on spontaneous activity in isolated bovine mesenteric lymphatics.
abstract: The mode of action of histamine on spontaneous contractions is isolated bovine mesenteric lymphatics was investigated by recording isometric tensions. Histamine at lower concentrations between about 5 x 10(-8) and 10(-6) M caused a dose-dependent deceleration of the rhythm of spontaneous contractions. Higher concentrations of histamine (more than about 5 x 10(-6) M) produced a dose-related acceleration of the rhythm in association with a slight elevation of basal tone in 115 of 173 preparations. In 58 of 173 lymphatic preparations, histamine at concentrations ranging from about 5 x 10(-8) to 10(-5) M caused only the positive chronotropic effect. The histamine-induced positive and negative chronotropic effects were unaltered by pretreatment with alpha- and beta-adrenergic antagonists but were dose-dependently antagonized by pretreatment with H1- or H2-blockers (diphenhydramine or cimetidine). The specific H1- and H2-agonists, 2-pyridylethylamine (2PEA) and dimaprit caused dose-related positive and negative chronotropic effects, respectively, on spontaneous contractions of isolated bovine mesenteric lymphatics. The effect of 2PEA was significantly blocked by pretreatment with 10(-6) M diphenhydramine, whereas the effect of dimaprit was suppressed by 10(-6) M cimetidine. These results suggest that both H1- and H2-receptors are located on the plasma membrane of smooth muscle cells in bovine mesenteric lymphatics, and that the excitations of H1- and H2-receptors respectively produce an acceleration and a deceleration of the rhythm of spontaneous contractions in lymphatic smooth muscles.
authors.affiliation: Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Kawai
authors.forename: T
authors.initials: T
authors.lastname: Ohhashi
mesh_terms: D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008208:Lymphatic System / Q000187:drug effects*; D008643:Mesentery; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology
chemical_list: D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D006632:Histamine; D007545:Isoproterenol; D009638:Norepinephrine; D010646:Phentolamine