The mechanisms of adaptation allowing resting freshwater mussels Anodontta cygnea to maintain their oxygen consumption (MO2) constant when the O2 partial pressure in the inspired water (PlO2) varied were studied at 13°C. Steady-state values of oxygen consumption and/or shell valve activity were determined at prefixed PlO2 for periods ranging from 2 to 15 days. Values of PO2, O2 concentration and acid-base status of arterial blood in the heart were determined after two days. MO2 was maintained constant over PlO2 ranging from 35 to less than 1 kPa. At 0.3 kPa it decreased by 50%. Valves remained open (and MO2 constant) most of the time even during a 4.5 day period at PlO2≈1.5 kPa. Between 35 and 1 kPa, blood PO2 at the heart level can remain low and within a narrow range independent of PlO2. Blood PCO2 increased at high PlO2 and decreased at low PlO2. Data are compared to previous results in crayfish and in wels (sheat-fish). On the basis of data similarity it is proposed that these three animals exhibit the same basic strategy for maintaining resting MO2 when PlO2 varies. This common feature relies mainly on the ability to maintain PO2 in the arterial blood at a value which is low and independent of PlO2. Hence, in terms of O2, homeostasis of the milieu intérieur is accomplished.
- Animal, freshwater mussel
- Arterial blood, composition in mussel
- Oxygen consumption, in mussel, dependent on inspired P
- pH, in mussel
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine