Abstract
Using our modified method of the isolated lung perfusion described by Sollmann and Von Oettingen, 1 we studied the peripheral action of ephedrine and pseudoephedrine on rabbit bronchial muscle. The arrangement of the perfusion was similar to that of Sollmann and Von Oettingen, but the borders of the lung were trimmed with sharp scissors so that the perfusion fluid was allowed to drain freely. The lung was lightly supported with a funnel covered with moist cotton to prevent drying, drops per minute through the funnel being reckoned as the rate of the bronchial outflow. The drugs took from half to one minute to reach the outflow, and 4 to 5 minutes for the concentration of drug of the outflow to be the same as that of the inflow. After 1 to 2 hours of perfusion with Tyrode solution, when the rate of outflow was 50 to 80 drops per minute, and when it had remained nearly constant for over 10 minutes, the perfusion of the ephedrine-Tyrode solution was started, and allowed to continue for 20 to 30 minutes (pH of ephedrine and Tyrode solution was found to be the same). Bronchial constriction was indicated by a decrease of outflow, and dilation by an increase. The bronchial muscle under this condition was found to be exceedingly sensitive to drugs, comparing with the method of Sollmann and Von Oettingen. After 6 to 7 hours of perfusion the bronchioles still responded to drugs. Injection of 0.5 cc. of pilocarpine 1:1,000,000 or atropine 1:1,000,000 into the connecting tube between lung and perfusion apparatus caused respectively a distinct constriction and dilation of the bronchioles.
The response of the bronchial muscle to ephedrine varied with the dosage.
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