The Regulation of Haemocyanin Oxygen Affinity during Emersion of the Crayfish Austropotamobius Pallipes Ii. an Investigation of in Vivo Changes in Oxygen Affinity

The oxygen-transporting properties of the haemolymph from the crayfish Austropotamobius pallipes were investigated. The haemolymph concentrations of K, Mg^ and Ca ions, together with the concentration of L-lactate were measured in crayfish before, during and after 24 h emersion. The concentrations of K and Mg"" increased during aerial exposure and returned to pre-emersion levels during immersed recovery. Large increases in the level of circulating L-lactate and Ca were correlated with shortand long-term aerial exposure respectively. Changes in the concentrations of these ions could also be correlated with changes in haemocyanin oxygen affinity. Reimmersion and recovery returned all parameters to near control values. The effect, on haemocyanin oxygen affinity, of the Bohr shift alone was calculated and compared with the change in oxygen affinity (AP50) actually determined during aerial exposure. These data were also compared with predictions, calculated from in vitro data, for the potentiation of haemocyanin oxygen affinity by Ca and L-lactate ions in aerially exposed crayfish. The physiological significance of the regulation of haemocyanin oxygen affinity by these ions is discussed.