1. Arterial plasma histamine concentrations, forced expiratory volume in 1.0 s (FEV1.0) and peak expiratory flow rate were determined in nine patients with exercise-induced asthma and in five control subjects before and after 8 min of cycle-ergometer exercise. 2. In the controls neither FEV1.0 nor peak expiratory flow rate fell by more than 5% in any individual during the 30 min postexercise period. The asthmatic patients all experienced a fall in FEV1.0 or peak expiratory flow rate, or both, of 15% or more in the period 5-20 min after completion of the exercise. 3. There was no difference between the control subjects and the asthmatic patients in the plasma histamine response to exercise. In both groups there was an insignificant rise of about 40% during exercise, although the initial levels were higher in the asthmatic patients. 4. The mean plasma histamine peak of the asthmatic patients preceded the mean maximal fall of FEV1.0 and peak expiratory flow rate by approximately 15 min. However, no positive correlation was found between rise in, or peak, plasma histamine levels and decrease in lung function. 5. Three non-atopic asthmatic patients had a significantly higher mean plasma histamine concentration during exercise than had the atopic subjects. 6. A strong positive correlation in asthmatic patients, and asthmatic and control subjects together was found between age and mean postexercise plasma histamine concentrations. 7. The results do not support a direct role for histamine in the production of exercise-induced asthma.
1.Arterial and venous whole blood and plasma histamine concentrations and eosinophil and basophil counts were determined in five patients with acute severe asthma who had not previously received steroid therapy, in five who had been maintained on steroid therapy and in a control group of nine patients with acute non-respiratory illnesses.2. No significant arteriovenous differences were observed for any of these measurements in any of the groups of patients. Significant net loss of arterial histamine does not therefore occur peripherally in acute asthma.3. When compared with the values for the controls, statistically significant increases were observed, in the group not receiving steroids, for arterial and venous whole blood histamine concentrations, eosinophil counts and basophil counts, and, in those receiving steroids, for the venous basophil counts.4. When compared with the venous plasma histamine concentration of normal subjects, that of the asthmatic subjects not receiving steroids was significantly raised.5. The venous plasma histamine concentration of the control group was also significantly higher than that of normal subjects, but less so than in the asthmatic subjects, suggesting that acute illness per se produces an increased plasma histamine concentration.
It is known that sympatho-adrenal control of airways is increased in asthma since blockade can cause severe bronchoconstriction in asthmatic individuals. It has not been established whether an altered catecholamine response to exercise plays any part in the production of the common symptom of exercise-induced asthma (EIA). We have investigated this indirectly by measuring arterial plasma cyclic nucleotide levels in 10 subjects with EIA and five normal subjects. Cyclic AMP, which in this context reflects fi stimulation, rose significantly by 25-4 % in the normal subjects during exercise, while there was no significant change during or after exercise ( < 5 %) in the asthmatic subjects. Cyclic GMP rose significantly after exercise in the asthmatic subjects. Six normal subjects repeated the protocol before and after inhalation of salbutamol aerosol, 1600 Htg daily for 18 days. This did not reduce the cAMP response to exercise, and we conclude that the diminished cAMP response of the asthmatic subjects was not caused by their medication. The results may indicate either impaired catecholamine production or endogenous fi receptor hyporesponsiveness in some asthmatic subjects and this may contribute to the development or EIA.
The effect of regular inhalation of betamethasone valerate (800 microgram daily) on exercise-induced asthma has been studied in 18 adult patients. The active aerosol was compared with placebo in a double-blind cross-over study, each inhaler being used for four weeks. Exercise tests after each period of treatment were performed using a cycle ergometer, care being taken to match the oxygen uptake during exercise each time a patient was tested. Twelve patients experienced less exercise-induced fall in peak expiratory flow rate after the corticosteroid inhaler, while six did not. This effect appeared to be independent of any alteration in base-line lung function, suggesting that it was due primarily to diminution of bronchial hyperreactivity. It is suggested that this change may have been due to interference with the synthesis or release of mediator substances from mast cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.