THE COMPARATIVE PHYSIOLOGICAL ACTIONS OF dl--PHENYLISOPROPYLAMINES II. BRONCHIAL EFFECT

¹ From the Laboratories of George Piness, M.D., Los Angeles, the Pharmacological Laboratory and the Department of Surgery, Division of Thoracic Surgery, of the University of California Medical School, San Francisco

1. Previous work on the bronchial effects of -phenylethylamine and its hydroxyphenyl type of derivatives is reviewed.

2. -phenylethylamine and -phenylisopropylamine, intravenously injected into pithed dogs or cats, dilate bronchi that exhibit natural or induced tone. Larger doses of these compounds than of epinephrine are required for appreciable dilator effect but definite evaluation is difficult. The bronchodilator effect of -phenylisopropylamine is more prolonged than that of -phenylethylamine but is of comparable intensity.

3. -4-hydroxyphenylethylamine and -4-hydroxyphenylisopropylamine, intravenously injected into pithed dogs or cats, dilate bronchi that exhibit natural or induced tone. Larger doses of these compounds than of epinephrine are required for appreciable dilator effect but definite evaluation is difficult. The bronchodilator effect of -4-hydroxyphenylisopropylamine is more prolonged than that of -4-hydroxyphenylethylamine but is of comparable intensity.

4. -3,4-dihydroxyphenylethylamine and -3,4-dihydroxyphenylisopropylamine, intravenously injected into pithed dogs or cats, dilate bronchi that exhibit natural or induced tone. Both these compounds are about one-fiftieth as effective as epinephrine in their bronchial effects, but exhibit a longer duration of effect, that of -3,4-dihydroxyphenylisopropylamine being the most prolonged.

5. Study of bronchodilator effects in pithed guinea pigs showed that the method is not generally useful for epinephrine or the compounds of the present study.

6. Bronchial perfusion effects, through the trachea of isolated guinea pig lungs, were not evident with the phenyl or hydroxyphenyl derivatives in the doses used. The dihydroxyphenyl derivatives did exhibit bronchodilator effects but quantitative comparisons of their effect will require further work.

7. A discussion is given of the apparent relationship between the relative pressor and bronchial effects of the compounds used for the present work.