Gas transport by hemocyanin-containing blood of the Cephalopod Octopus dofleini

O2 and CO2 dissociation curves have been obtained for the hemocyanin-containing blood from the large Cephalopod, Octopus dofleini. The oxyhemocyanin curves showed a typical sigmoid shape. Values for T50 and T100 at 11 C and 0.4 mm Hg Pco2 were 15 and 70 mm Hg Po2, respectively. The amount of dissolved O2 in the blood at higher Po2 was considerable and could reach 10% of the total O2. The O2 capacity averaged 3.06 vol %. Dissolved carbon dioxide decreased the affinity of hemocyanin (Hcy) for O2 (Bohr effect) and reduced the O2 content at saturation (Root effect). At increased temperature the affinity to oxygen was decreased. The CO2 dissociation curves showed a moderate CO2-combining power. A distinct difference in CO2-combining power between oxygenated and reduced blood was present (Haldane effect). This difference was limited to the physiological range of Pco2. Increased temperature decreased the CO2-combining power. The buffering capacity of the blood was low, but in the physiological range of pH there was a distinct difference in buffering ability between reduced and oxygenated blood. The findings are discussed in relation to other marine animals.