Pulmonary mechanics during hypoxia in spontaneously breathing anesthetized rabbits.

Changes in lung mechanics were measured during hypoxia (FIO2 = 0.10 during 5 min) in spontaneously breathing anesthetized rabbits. In intact animals, hypoxia induced scattered variations in total lung resistance (RL) (decrease, increase or no alteration) and dynamic lung compliance (CL), whereas in carotid body denervated animals it was accompanied by an almost constant decrease in RL (-12%); but if a subsequent vagotomy was performed, there was no significant variation in RL. In animals which had been only vagotomized, CL decreased significantly during hypoxia (-23%) without any associated change in RL. So, the arterial chemoreceptor mediated bronchoconstrictor effects due to hypoxia could be normally masked by the dilator effects (metabolic and/or sympathetic) on the airways.