title: Effects of selective phosphodiesterase inhibitors on platelet-activating factor- and antigen-induced airway hyperreactivity, eosinophil accumulation, and microvascular leakage in guinea pigs.
abstract: There is currently interest in the potential use of selective inhibitors of cyclic nucleotide phosphodiesterases (PDE) in the treatment of asthma. In this study we examined the effects of three selective PDE inhibitors, milrinone (PDE III), rolipram (PDE IV) and zaprinast (PDE V), on the broncoconstriction produced by antigen and histamine, the airway hyperreactivity and microvascular leakage after aerosol exposure to platelet-activating factor (PAF) and antigen, and the antigen-induced eosinophil infiltration in guinea-pig lung. Inhaled rolipram (0.01-10 mg ml-1) inhibited dose dependently the bronchospasm produced by aerosol antigen (5 mg ml-1) an anaesthetised, ventilated guinea-pigs. Rolipram (10 mg ml-1) produced maximal inhibition of antigen-induced bronchoconstriction but only partial inhibition of the response to aerosol histamine (1 mg ml-1). Milrinone and zaprinast (each 10 mg ml-1) showed weak, or no, inhibitory effects against bronchoconstriction produced by aerosol antigen or histamine. Pretreatment with rolipram (10 mg kg-1, i.p.) prevented airway hyperreactivity to histamine which develops 24 h after exposure of conscious guinea-pigs to aerosol PAF (500 micrograms ml-1) or antigen (5 mg ml-1). The pulmonary eosinophil infiltration obtained with 24 h of antigen-exposure was inhibited by rolipram. In contrast, milrinone and zaprinast (each 10 mg kg-1, i.p.) failed to reduce either the airway hyperreactivity of the eosinophil accumulation in these animals. Rolipram (1-10 mg ml-1) reduced the extravasation of Evans blue after aerosol PAF (500 micrograms ml-1) at all airway levels while a lower dose (0.1 mg ml-1) was only effective at intrapulmonary airways. Rolipram (0.01-1 mg ml-1) markedly reduced airway extravasation produced by inhaled antigen (5 mg ml-1). Zaprinast (1-10 mg ml-1) was also effective against airway microvascular leakage produced by aerosol PAF or antigen while milrinone (10 mg ml-1) had no antiexudative effect. These data support previous suggestions that pharmacological inhibition of PDE IV results in anti-spasmogenic and anti-inflammatory effects in the airways and may be useful in the treatment of asthma.
authors.affiliation: Department of Pharmacology, University of Valencia, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Ortiz
authors.forename: J M
authors.initials: JM
authors.lastname: Vallés
authors.forename: M
authors.initials: M
authors.lastname: Martí-Cabrera
authors.forename: J
authors.initials: J
authors.lastname: Cortijo
authors.forename: E J
authors.initials: EJ
authors.lastname: Morcillo
mesh_terms: D000818:Animals; D001249:Asthma / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000378:metabolism*; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010972:Platelet Activating Factor / Q000187:drug effects*; D011760:Pyrrolidinones / Q000494:pharmacology; D012137:Respiratory System / Q000187:drug effects*; D020889:Rolipram
chemical_list: D010726:Phosphodiesterase Inhibitors; D010972:Platelet Activating Factor; D011760:Pyrrolidinones; D006632:Histamine; D020889:Rolipram