Adaptations to diving in the harbor seal— gas exchange and ventilatory response to CO₂

¹ Departments of Medicine, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, University of Alabama, Birmingham, Alabama, and Mount Desert Island Biological Laboratory, Salisbury Cove, Maine
² Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, University of Alabama, Birmingham, Alabama, and Mount Desert Island Biological Laboratory, Salisbury Cove, Maine

Pulmonary gas exchange and the ventilatory response to CO₂ were measured in six female harbor seals, Phoca vitulina. Mean Paco₂ (48 ± 6 mm Hg) is higher in the seal and mean Pao₂ (88 ± 9 mm Hg) is lower than the corresponding value in man. The seal shows a depressed ventilatory response to CO₂ both in terms of slope and intercept of CO₂ response curves. The depressed respiratory center sensitivity to CO₂ presumably is an adaptative mechanism permitting prolonged diving in this species.

Key Words: Phoca vitulina • depressed respiratory center sensitivity

Submitted on June 7, 1963

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