The effects of repeated exercise-induced bronchospasm on nonspecific (nonallergenic) bronchial responsiveness (NSBR) to histamine were studied in 12 asthmatic patients (6 F, 6 M). Baseline NSBR, determined by the provocative concentration of histamine giving a 20% fall in FEV1 (PC20), ranged from 0.41 to 10.2 mg/ml (geometric mean ± SD: 2.6 ± 2.5). Each subject performed three consecutive exercises on the ergometer for 6 min at 70% of their VO2 max. Each test was preceded and followed by a histamine inhalation test (HIT). On a control day, 4 HIT were done at 1 h interval, without intercurrent exercise. A significant reduction in histamine responsiveness was observed on control day from the first to the fourth HIT. On exercise day, a mean percent fall in FEV1 of 19.4 ± 12.9, 16.2 ± 12.2 and 15.8 ± 12.7 was observed after the three consecutive exercises but no significant difference could be found between the four PC20 measurements. Four subjects showed refractoriness to the second exercise and no change in the bronchial response to histamine was observed during the refractory period. In conclusion, (1) repeated exercises do not change NSBR; (2) the refractory period after exercise is not due to a change in NSBR, and (3) a tachyphylaxis to histamine occurs in some subjects after repeated inhalations of histamine

Keywords:
Exercise-induced asthma, Refractory period, Nonspecific bronchial responsiveness, Histamine tachyphylaxis
This content is only available via PDF.
© 1987 S. Karger AG, Basel
1987
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.