Ontogenetic modification of the hypercapnic ventilatory response in the zebra finch

Abstract

We investigated the effect of exposure to CO 2 during development on the adult ventilatory response to CO 2 of zebra finches. Developing zebra finches were exposed to chronic hypercapnic respiratory environments as embryos, as nestlings or during both developmental periods. Their responsiveness to CO 2 was then measured following a 125–135 day post-fledging deacclimation period. At a Fl CO 2 of 0.06, mean ventilation of adult finches in the three groups was 74.8, 61.3 and 65.8%, respectively, of that of finches reared under normocapnic conditions. These data indicate that adult acute ventilatory responsiveness to CO 2 in birds may be in part determined by CO 2 exposure during early development and may help explain the observation that fossorial and semifossorial species of birds and mammals, that naturally encounter high CO 2 conditions in their burrows, have a blunted hypercapnic ventilatory response.