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

¹ Institute of Respiratory Physiology, Firland Sanatorium, and Departments of Zoology and Physiology, University of Washington, Seattle, Washington

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.

Key Words: Cephalopods • gas transport • hemocyanin • acid-base balance • oxyhemocyanin dissociation curve • CO₂ dissociation curve • Bohr effect • Haldane effect • Root effect

Submitted on February 23, 1965