Lung mechanics and end-expiratory lung volume during hypoxia in rats

M. Bonora, M. Vizek
1999 Journal of applied physiology  
Bonora, M., and M. Vizek. Lung mechanics and endexpiratory lung volume during hypoxia in rats. J. Appl. Physiol. 87(1): 15-21, 1999.-We investigated whether an hypoxia-induced increase in airway resistance mediated by vagal efferents participates in the increase in end-expiratory lung volume (EELV) observed in hypoxia. We also assessed the contribution of the end-expiratory activity of the diaphragm (DE) to this phenomenon. Therefore, we measured EELV, total lung resistance (RL), dynamic lung
more » ... RL), dynamic lung compliance (Cdyn), DE, and minute ventilation (V E) in anesthetized rats during normoxia and hypoxia (10% O 2 ) before (control) and after administration of atropine or saline. In the control group, hypoxia increased EELV, Cdyn, DE, and V E but slightly decreased RL. These changes were unaffected by saline or atropine, except that, in the atropine-treated rats, hypoxia did not change RL. These results suggest that 1) the increase in EELV observed in hypoxia cannot result from an increase in airway resistance; 2) the increased and persistent activity of inspiratory muscles during expiration is the most likely cause of the increase in EELV during hypoxia; and 3) the decrease in RL induced by hypoxia could result from the increase in lung volume including EELV. total lung resistance; dynamic lung compliance; end-expiratory activity of the diaphragm; postinspiratory inspiratory activity; atropine; braking of expiratory airflow 8750-7587/99 $5.00
doi:10.1152/jappl.1999.87.1.15 pmid:10409553 fatcat:ovwdb6pxcnhe3hn5hfguv27qhy