Correlation between convection requirement and carotid body responses to hypoxia and hemoglobin affinity: comparison between two rat strains.

We tested the hypothesis that differences in ventilatory ([Formula: see text]) or convection requirement ([Formula: see text]/[Formula: see text]O response to hypoxia would be correlated with differences in hemoglobin (Hb) oxygen affinity between two strains of rats, as they have been shown to be among several species of mammals, birds and reptiles. Brown Norway (BN) rats reduce metabolism more than they increase ventilation in response to hypoxia and both the ventilatory and convection requirement responses to hypoxia are lower in the BN than the Sprague-Dawley (SD) rat. The lower threshold of the ventilation/convection requirement responses of the BN to hypoxia are associated with a higher affinity Hb than the SD rats, (P values of 32.

Effects of aerobic and anaerobic metabolic inhibitors on avian intrapulmonary chemoreceptors.

Birds have rapidly responding respiratory chemoreceptors [intrapulmonary chemoreceptors (IPC)] that provide vagal sensory feedback about breathing pattern. IPC are exquisitely sensitive to CO(2) but are unaffected by hypoxia. IPC continue to respond to CO(2) during hypoxic and even anoxic conditions, suggesting that they may generate ATP needed for signal transduction anaerobically.

Ventilatory and metabolic responses of burrowing owls, Athene cunicularia, to moderate and extreme hypoxia: analysis of the hypoxic ventilatory threshold vs. hemoglobin oxygen affinity relationship in birds.

We measured ventilation, oxygen consumption and blood gases in burrowing owls (Athene cunicularia) breathing moderate and extreme hypoxic gas mixtures to determine their hypoxic ventilatory threshold (HVT) and to assess if they, like other birds and mammals, exhibit a relationship between HVT and hemoglobin O2 affinity (P(50)) of their blood. An earlier report of an attenuated ventilatory responsiveness of this species to hypoxia was enigmatic given the low O2 affinity (high P(50)) of burrowing owl hemoglobin. In the current study, burrowing owls breathing 11% and 9% O2 showed a significantly elevated total ventilation.