Oxygen uptake and haemocyanin oxygen affinity of Potamonautes warreni Calman after exercise

Abstract

The MO₂ values for exhaustively exercised crabs in water medium or air medium are nearly twice the values found for pre-exercised crabs. The l-lactate concentration in the haemolymph increases from 0,75 ± 0,37 mmol to 9,63 ± 2,1 mmol in P. warreni after air exercise, a value similar to those for other terrestrial and aquatic crabs. The same increase in the l-lactate concentration was found for water-exercised crabs. The pH in the haemolymph decreases from 7,51 (SD 0,07) to 7,11 (SD 0,08) after the 20 min air medium exercise and from 7,521 (SD 0,06) to 7,229 (SD 0,09) after 20 min exercise in water medium. In both respiratory media this causes a lowering in the haemocyanin oxygen affinity with a Bohr-factor of – 1,05 whilst the haemocyanin-oxygen co-operativity increases from 3,0 to 3,7. Preliminary in vitro experiments indicate that l-lactate (as an acid metabolite) is mainly responsible for the Bohr-effect.