The effect of progressive hypoxia on respiration in the toad Bufo marinus.
1. As Bufo marinus became progressively hypoxic over a period of 90 min, there was a rise in arterial pH, presumably brought about by hyperventilation. The alkalosis gradually disappeared when oxygen levels became very low. It is suggested that this is the result of a respiratory or a metabolic pH adjustment, or both. 2. Hypoxic animals developed a characteristic breathing pattern in which discrete periods of lung ventilations alternated with buccal oscillations or respiratory pauses. 3. A pronounced bradycardia was associated with the concomitant decline of inspired and arterial PO2. 4. Although respiratory rates were greater than normal resting values in the initial stages of post-hypoxia, the pre-exposure breathing pattern was quickly restored. Following recovery from bradycardia (60 min), the breathing rates, arterial blood gases and pHa returned to normal within 30 min.
The effect of progressive hypoxia on respiration in the toad Bufo marinus. 1. As Bufo marinus became progressively hypoxic over a period of 90 min, there was a rise in arterial pH, presumably brought about by hyperventilation. The alkalosis gradually disappeared when oxygen levels became very low. It is suggested that this is the result of a respiratory or a metabolic pH adjustment, or both. 2. Hypoxic animals developed a characteristic breathing pattern in which discrete periods of lung ventilations alternated with buccal oscillations or respiratory pauses. 3. A pronounced bradycardia was associated with the concomitant decline of inspired and arterial PO2. 4. Although respiratory rates were greater than normal resting values in the initial stages of post-hypoxia, the pre-exposure breathing pattern was quickly restored. Following recovery from bradycardia (60 min), the breathing rates, arterial blood gases and pHa returned to normal within 30 min.