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The excretion of histamine (Hi) and its metabolite methylhistamine (MeHi) was determined in separated fractions of urine up to 12h after standardized allergen provocations in 18 adult patients with defined extrinsic bronchial asthma. The main histamine metabolite, methylimidazoleacetic acid (MelmAA), was measured in six of the patients. After positive provocations (decrease in FEV1 > 20%) the excretion of Hi was significantly increased during 3h and that of MeHi during 4h after challenge. Negative provocations (decrease in FEV1 < 20%) were not followed by any changes in the excretion of Hi and Mehi. MelmAA excretion increased in five out of six patients after positive provocation. It was calculated that the increased excretion of Hi and its metabolites after a positive provocation corresponded to a release of about 1 mg histamine in the body or about 1 μg/g lung tissue if all histamine was liberated in the lung. Pretreatment with two anti-allergic drugs, disodium cromoglycate and ICI 74.917, giving significant allergen protection, resulted in a smaller increase of the excretion of both Hi and MeHi, indicating an inhibition of histamine release in vivo. [ABSTRACT FROM AUTHOR]

Histamine metabolism was investigated in patients with intrinsic asthma, during the acute phase and in remission, by determination of the urinary excretion of histamine metabolites. During acute attacks the excretion of methythistamine (MeHi) and 1- methyl-4-unidazoleacetic acid (MeImAA) was significantly increased compared with healthy subjects. The excretion of MeHi was significantly increased during acute attacks compared with remission. The excretion of MeImAA was also increased, but the difference was not significant. The correlation between the excretion of MeHi and MeImAA was highly significant, Corticosteroids, given to some patients during remission, did not affect the excretion of histamine and its metabolites. Smoking and respiratory infection during the acute attacks were both accompanied by increased excretion of MeHi, The results indicate that there is an increased histamine turnover in acute attacks of intrinsic bronchial asthma. [ABSTRACT FROM AUTHOR]

Ten female patients with asthma-like symptoms but negative asthma tests (study group) were compared with 10 female asthmatics in an exercise test with and without pretreatment with β2-stimulants. The aim was to determine whether the asthma-like symptoms in the patients of the study group could be explained by bronchoconstriction, circulatory abnormalities, or physical unfitness when provoked physically, and whether the exercise test could be used to distinguish these patients from asthmatics. Without pretreatment, the asthma group reacted with bronchoconstriction, as indicated by postexercise systematic changes in PEFR, FEV1, FVC, and SaO2, which were not seen in the study group. The groups differed in the ratings of "difficulty in getting air", as only the asthma group had significantly lower ratings when pretreated. The study group's mean test performance was 94 W; the asthma group's was 106 W. The low performance was not explained by disturbances in heart rate, electrocardiogram, or blood pressure or physical unfitness. The exercise test was found to distinguish between the groups, especially for bronchoconstriction, oxygen saturation, and ratings of dyspnea. It could be used complementary to lung function tests to eliminate bronchoconstriction, circulatory abnormalities, and physical unfitness as a cause of the asthma-like symptoms. [ABSTRACT FROM AUTHOR]