Temperature and the oxygen-hemoglobin dissociation curve of the harbor seal, Phoca vitulina

David C. Willford, Andrew T. Gray, Steven C. Hempleman, Randall W. Davis, Esther P. Hill

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


To determine the effect of temperature and pH on oxygen-hemoglobin affinity of the harbor seal, we measured 61 biotonometric oxygen-hemoglobin dissociation curves on blood from 5 seals at 3 temperatures and a range of pH values. The average (± SEM) hemoglobin concentration was 3.44 ± 0.15 mM, nearly 50% greater than found in normal humans. At pH 7.4 the P50 (partial pressure of O2 at 50% hemoglobin saturation) ± SEM values were 22.4 ± 0.6, 25.3 ± 0.5, and 28.5 ± 0.4 Torr at 33,37 and 41°C, respectively. The effect of temperature on oxygen-hemoglobin affinity, (Δlog P50/ΔT) was 0.014 ± 0.001 at pH 7.4, significantly lower than that observed in human and dog blood. This low temperature sensitivity may facilitate oxygen off-loading from hemoglobin when temperature gradients exist within the animal or as tissue temperature decreases during a dive. Temperature did not significantly affect the Hill coefficient 'n' (shape) of the dissociation curve which averaged 2.43 ± 0.04 at 37°C. The fixed-acid Bohr coefficient (Δlog P50/ΔpH) was -0.606 ± 0.032 at 37°C and increased with temperature. This relatively large value for the Bohr coefficient was similar to those previously reported for the Northern Elephant, Bladdernose, and Weddell Seals, and may facilitate oxygen off-loading as acidosis develops during a dive.

Original languageEnglish (US)
Pages (from-to)137-144
Number of pages8
JournalRespiration Physiology
Issue number2
StatePublished - Feb 1990


  • Bohr effect
  • Oxygen-hemoglobin affinity
  • Oxygen-hemoglobin dissociation curve
  • Temperature

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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