Respiration of the emersed shore crab at variable ambient oxygenation

Autor: Pierre Dejours, Jean-Paul Truchot
Rok vydání: 1988
Předmět:
Zdroj: Journal of Comparative Physiology B. 158:387-391
ISSN: 1432-136X
0174-1578
DOI: 10.1007/bf00695338
Popis: In the intertidal shore crab,Carcinus maenas, pH and $$P_{CO_2 } $$ values of the prebranchial venous hemolymph, $${\text{p}}H\bar v$$ and $$P\bar v_{CO_2 } $$ , the PO2 values of the arterialized cardiac hemolymph, $$P{\text{a}}_{O_2 } $$ , were measured, and the ventilatory activity was assessed by measuring the hydrostatic pressures at the exits of the epibranchial cavities, under four environmental conditions: normoxic water, normoxic air, hypoxic gas, hyperoxic gas. In the crab breathing normoxic air, $$P{\text{a}}_{O_2 } $$ was lower and $$P\bar v_{CO_2 } $$ higher than in animals breathing normoxic water. With the switch to hypoxic gas, ventilation increased and $$P{\text{a}}_{O_2 } $$ and $$P\bar v_{CO_2 } $$ decreased. With the switch to hyperoxic gas, ventilation decreased, $$P{\text{a}}_{O_2 } $$ and $$P\bar v_{CO_2 } $$ increased and $${\text{p}}H\bar v$$ decreased. Thus these crabs breathing air were not as well oxygenated as when breathing air-equilibrated water, and because of their low $$P{\text{a}}_{O_2 } $$ , they were relatively hypervetilating and hypocapnic compared to air-breathing vertebrates. Hyperoxic breathing, increasing $$P{\text{a}}_{O_2 } $$ and reducing ventilatory drive, led to increased $$P\bar v_{CO_2 } $$ . Conversely, $$P\bar v_{CO_2 } $$ was reduced by hypoxic breathing. These observations suggest that the gas exchanger of intertidal crabs is not as successfully designed for air breathing as that of land-colonizing insects and air-breathing vertebrates.
Databáze: OpenAIRE
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