[Inhibitory effect of prostaglandin I2 on the increase of airway responsiveness induced by inhaled thromboxane A2 mimetic U-46619 in dogs].
To investigate the effect of prostaglandin I2 (PGI2) on the increase of airway responsiveness induced by inhaled thromboxane A2 (TxA2), we measured the airway responsiveness to inhaled methacholine (Mch) after inhalation of TxA2 mimetic U-46619 alone and after inhalation of U-46619 in combination with PGI2 (U-46619/PGI2) in six dogs. Airway responsiveness to Mch was determined by Astograph (7Hz oscillation method). Inhalation of U-46619 was carried out for five minutes at a half of minimum threshold concentration, and the concentration of PGI2 was double that of U-46619. Inhaled U-46619 significantly increased airway responsiveness to Mch (p less than 0.01). However the airway responsiveness to Mch did not increase following inhalation of U-46619/PGI2, and the increase of airway responsiveness to Mch induced by inhaled U-46619 was inhibited significantly by PGI2 (p less than 0.01). PGI2 inhalation alone did not affect the basal airway responsiveness to Mch. These results indicate that PGI2 protects the hyperresponsiveness induced by TxA2 inhalation in dogs.
Imai
T
T
First Department of Internal Medicine, School of Medicine, Showa University.
Adachi
M
M
Idaira
K
K
Sugeta
A
A
Hiyama
T
T
Suganuma
T
T
Takahashi
T
T
Tanaka
Y
Y
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000403:Airway Resistance / Q000187:drug effects*; D000818:Animals; D016084:Bronchoconstriction / Q000187:drug effects*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D011464:Epoprostenol / Q000494:pharmacology*; D016210:Methacholine Chloride / Q000494:pharmacology; D011450:Prostaglandin Endoperoxides, Synthetic / Q000037:antagonists & inhibitors*
D011450:Prostaglandin Endoperoxides, Synthetic; D016210:Methacholine Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D011464:Epoprostenol