title: Tachyphylaxis to inhaled isoproterenol and the effect of methylprednisolone in dogs.
abstract: Acute tachyphylaxis can be induced to inhaled isoproterenol (ISO) in anesthetized, closed-chested mongrel dogs. The responsiveness to ISO measured as the percent reduction in methacholine-induced bronchoconstriction was decreased significantly (p less than 0.01) after a 1-hr period of repeated ISO inhalations (ISO-loading). Intravenous administration of methylprednisolone (1 mg/kg) reversed the decrease in responsiveness to ISO.
mesh_terms: D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007545:Isoproterenol / Q000009:adverse effects*; D008688:Methacholine Compounds / Q000494:pharmacology; D008775:Methylprednisolone / Q000627:therapeutic use*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000276:immunology; D013618:Tachyphylaxis
chemical_list: D008688:Methacholine Compounds; D011942:Receptors, Adrenergic, alpha; D007545:Isoproterenol; D009638:Norepinephrine; D008775:Methylprednisolone