Increases in arterial blood oxygen during exercise in the lemon shark (Negaprion brevirostris)

P. G. Bushnell, P. L. Lutz, J. F. Steffensen, A. Oikari, S. H. Gruber

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39 Scopus citations


Polyethylene cannulae were implanted in pre- and post-branchial blood vessels allowing nonstressful blood sampling over a variety of activity ranges in an active tropical elasmobranch, the lemon shark (Negaprion brevirostris). The P50 was found to be 11.8 Torr at 24°C and pH of 7.7. A Bohr shift of -0.36 was also found. Blood Po2 and oxygen content were measured during rest, routine swimming, and exercise in unanesthetized, free swimming juveniles. Under all conditions venous oxygen levels were low with venous Po2 of 7.1±2.7 Torr, and venous oxygen content ( {Mathematical expression}) of 0.56±0.4 vol%. However, a large variability was found in arterial blood measurements. Arterial Po2 ranged from 7 to 80 Torr, while arterial oxygen content (Cao2) varied from 1.6 vol% to 6.8 vol% among ten experimental animals. A significant increase in arterial Po2, oxygen content, and hematocrit was noted during increased activity. Since the venous system provides little or no oxygen reserve, increased oxygen extraction from the blood ( {Mathematical expression}) appears to be met by an increase in Cao2 rather than a decrease in {Mathematical expression}. Mechanisms to accomplish this may include increasing hematocrit and vacular gill shunts.

Original languageEnglish (US)
Pages (from-to)41-47
Number of pages7
JournalJournal of Comparative Physiology ■ B
Issue number1
StatePublished - Mar 1 1982

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Physiology
  • Animal Science and Zoology
  • Endocrinology


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