AJP - Lung Cellular and Molecular Physiology, Vol 269, Issue 2 227-L233, Copyright © 1995 by American Physiological Society

ARTICLES

Time course of airway hyperresponsiveness and remodeling induced by hyperoxia in rats

J. L. Szarek, H. L. Ramsay, A. Andringa and M. L. Miller
Department of Pharmacology, Marshall University School of Medicine, Huntington, West Virginia 25704-9388, USA.

The purpose of this study was to answer two questions concerning hyperoxia-induced airway hyperresponsiveness: 1) What is the time course of the development of airway hyperresponsiveness? 2) What is the relationship between the increase in responsiveness and smooth muscle area? Segments of intrapulmonary bronchi were isolated from male Sprague-Dawley rats that had been exposed to 80-85% O2 for a period of 1, 3, 5, or 7 days and from aged-matched control animals that breathed room air. Hyperoxia increased the sensitivity (log concentration or frequency that elicited a half-maximal response) and reactivity (maximum tension developed) of the airways to electrical field stimulation (EFS) after 3, 5, and 7 days; sensitivity to acetylcholine was not affected, but reactivity was increased after 7 days. Hyperoxia increased smooth muscle area beginning 5 days after commencing the exposure. After normalizing tension responses to smooth muscle area, reactivity of the airways to the stimuli was not different between the two groups, but sensitivity to EFS was still increased. The increase in reactivity observed after 5 and 7 days of exposure can be explained by an increase in smooth muscle area that occurred at these time points. The fact that the sensitivity of the airways to EFS remained increased after normalization, together with the fact that the increase in airway responsiveness after 3 days of exposure occurred at a time when smooth muscle area was not different from control, suggests that mechanisms other than increased smooth muscle area contribute to the development of hyperoxia-induced airway hyperresponsiveness.

This article has been cited by other articles:

				M. J. Mhanna, M. A. Haxhiu, M. A. Jaber, R. W. Walenga, C.-H. Chang, S. Liu, and R. J. Martin Hyperoxia impairs airway relaxation in immature rats via a cAMP-mediated mechanism J Appl Physiol, May 1, 2004; 96(5): 1854 - 1860. [Abstract] [Full Text] [PDF]

				F. Petak, W. Habre, Y. R. Donati, Z. Hantos, and C. Barazzone-Argiroffo Hyperoxia-induced changes in mouse lung mechanics: forced oscillations vs. barometric plethysmography J Appl Physiol, June 1, 2001; 90(6): 2221 - 2230. [Abstract] [Full Text] [PDF]

				S. C. Iben, I. A. Dreshaj, C. F. Farver, M. A. Haxhiu, and R. J. Martin Role of endogenous nitric oxide in hyperoxia-induced airway hyperreactivity in maturing rats J Appl Physiol, September 1, 2000; 89(3): 1205 - 1212. [Abstract] [Full Text] [PDF]

				T. Fukunaga, P. Davies, L. Zhang, Y. Hashida, and E. K. Motoyama Prolonged high intermittent positive-pressure ventilation induces airway remodeling and reactivity in young rats Am J Physiol Lung Cell Mol Physiol, September 1, 1998; 275(3): L567 - L573. [Abstract] [Full Text] [PDF]