ISSN:
1432-136X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. Chronically normoxic, hypoxic ( $$PI_{O_2 }$$ =60 Torr) or hyperoxic ( $$PI_{O_2 }$$ ≃600 Torr) crayfish (Astacus leptodactylus,n=51) were exposed to one-hour hypercapnic periods (inspired $$P_{CO_2 }$$ , $$PI_{CO_2 }$$ =2, 4 or 6 Torr; inspired pH, pHi=8.00, 7.70 or 7.52; reference $$PI_{CO_2 }$$ =0.8 Torr and pHi=8.40) either in the morning or the evening, all year round. The ventilatory requirement (i.e. the volume of water breathed to obtain a unit quantity of oxygen) and the ventilatory frequency were followed. In 18 other crayfish, ventilation, oxygen consumption and the ventilatory requirement were measured during spontaneous daily and yearly changes in oxygen consumption. 2. The ventilatory responses to CO2 stimuli varied greatly. No response was observed in 45% of morning experiments on normoxic crayfish. Hyperventilation, when present, was greater the higher the reference value of the ventilatory requirement and the value of $$PI_{CO_2 }$$ . Since the ventilatory requirement is higher in crayfish with a high O2 consumption, it is suggested that the CO2 sensitivity increases with metabolism. In CO2-reponsive crayfish, the higher the water oxygenation, the less the CO2-induced hyperventilation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00683217
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