Equine influenza virus enhances responsiveness of guinea-pig tracheal muscle to isoprenaline.
Groups of guinea-pigs were vaccinated with equine influenza A-1 virus and helically-cut tracheal strips were subsequently contracted to carbachol (EC50) and relaxed to isoprenaline at 3, 5 and 10 days post-vaccination. Tracheas from another group were contracted to phenylephrine in the presence of propranolol. Compared to controls, responses to isoprenaline in virus-infected tracheas were significantly potentiated at days 3 and 10. Virus infection significantly inhibited tracheal responsiveness to phenylephrine. It appears that enhancement of isoprenaline may be caused by diminished reactivity of the alpha-adrenoceptor system, thus promoting airway dilatation caused by the beta-adrenoceptor agonist.
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004347:Drug Interactions; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009980:Influenza A virus; D007545:Isoproterenol / Q000494:pharmacology*; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects*
D010656:Phenylephrine; D002217:Carbachol; D011433:Propranolol; D007545:Isoproterenol