Studies on Bronchial Hypersensitivity in Asthmatic Patients : I. Evaluation of hypersensitivity threshold by inhalation of acetylcholine histamine and serotonin

Abstract

In an attempt to compare the amounts of drugs which reqired to produce a 20% decrease of I"FEV, 75 asthmatic patients and 10 healthy volunteers were inhalated with graded doses of acetylcholine, histamine and serotonin. 1) The bronchial hypersensitivity thresholds for acetylcholine and histamine were significantly lower in asthmatic than than in normal subjects. 2) The hypersensitivity threshold for serotonin was approximately the same in asthmatic and normal subjects. However, in the absence of appreciable decrease of the threshold, asthma-like attack was produced in response to serotonin inhalation in one asthmatic patient. 3) When acetylcholine, histamine and serotonin were compared in the same asthmatic patients, the hypersensitivity threshold for serotonin was the highest, its threshold for histamine was the least and its threshold for acetylcholine was the intermediate. It was also shown that the patients, who had high threshold for threshold for acetylcholine, had high threshold for histamine. 4) In order to test day to day variations of hypersensitivity threshold for acetylcholine and histamine, hypersensitivity thresholds were repeatedly measured in several occations in the same asthmatic patients. The thresholds for these two drugs, however, were not so constant. Although threshold for acetyl-holine was in most cases higher than that for histamine, the fluctuation pattern of acetylcholine was not soparallel to that of histamine. 5) In some particular healthy volunteers, moderate hypersensitivity thresholds for both acetyl-choline and histamine was demonstrated.