COMPARISON OF BRONCHIAL RESPONSES TO PROSTAGLANDIN-F2-ALPHA AND METHACHOLINE

[摘要] Bronchial responsiveness to prostaglandin(PG)F2.alpha. was examined to determine its applicability in clinical practice and to compare it with bronchial responsiveness to the pharmacologically dissimilar agent, methacholine. Inhalation tests with 2-fold increasing concentrations of the 2 agents were performed in 19 asthmatic and 4 normal human subjects. Results were expressed as the provocation concentration causing a 20% fall in forced expiratory volume in 1 s (PC20). The range of concentrations required to determine the PC20 was greater with PGF2.alpha. (0.0001 to < 5 mg/ml) than that with methacholine (0.07-30.96 mg/ml). Side effects of cough, retrosternal irritation and expectoration of sputum were more frequent after PGF2.alpha.. Repeat measurements in the same subjects showed that responses to PGF2.alpha. were as highly reproducible as reported with methacholine, and there was a cumulative dose effect. PC20 PGF2.alpha. correlated with PC20 methacholine, but to a lesser degree than was previously demonstrated between histamine and methacholine. The poorer correlation was explained by the results of 4 subjects tolerant to PGF2.alpha. relative to methacholine, 3 of whom were aspirin (ASA) intolerant; the correlation was much stronger when these subjects were excluded from analysis. PGF2.alpha. apparently is not a suitable agent to use in clinical practice to measure nonspecific bronchial responsiveness because of the wide dose range and unpleasant side effects. Bronchial responsiveness of different individuals to PGF2.alpha. and methacholine is usually well correlated and is unrelated to specific receptor activity. There is a relative reduction in responsiveness to PGF2.alpha. in some asthmatics, particularly those with ASA intolerance.