Blood flow and metabolic regulation in seal muscle during apnea

Paul J. Ponganis, Ulrike Kreutzer, Torre K. Stockard, Ping Chang Lin, Napapon Sailasuta, Tuan Khan Tran, Ralph Hurd, Thomas Jue

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


In order to examine myoglobin (Mb) function and metabolic responses of seal muscle during progressive ischemia and hypoxemia, Mb saturation and high-energy phosphate levels were monitored with NMR spectroscopy during sleep apnea in elephant seals (Mirounga angustirostris). Muscle blood flow (MBF) was measured with laser-Doppler flowmetry (LDF). During six, spontaneous, 8-12 min apneas of an unrestrained juvenile seal, apneic MBF decreased to 46±10% of the mean eupneic MBF. By the end of apnea, MBF reached 31±8% of the eupneic value. The t1/2 for 90% decline in apneic MBF was 1.9±1.2 min. The initial post-apneic peak in MBF occurred within 0.20±0.04 min after the start of eupnea. NMR measurements revealed that Mb desaturated rapidly from its eupenic resting level to a lower steady state value within 4 min after the onset of apnea at rates between 1.7±1.0 and 3.8±1.5% min -1, which corresponded to a muscle O2 depletion rate of 1-2.3 ml O2 kg-1 min-1. High-energy phosphate levels did not change with apnea. During the transition from apnea to eupnea, Mb resaturated to 95% of its resting level within the first minute. Despite the high Mb concentration in seal muscle, experiments detected Mb diffusing with a translational diffusion coefficient of 4.5×10-7cm 2s-1, consistent with the value observed in rat myocardium. Equipoise PO2 analysis revealed that Mb is the predominant intracellular O2 transporter in elephant seals during eupnea and apnea.

Original languageEnglish (US)
Pages (from-to)3323-3332
Number of pages10
JournalJournal of Experimental Biology
Issue number20
StatePublished - Oct 15 2008
Externally publishedYes


  • Doppler
  • Hemodynamics
  • Muscle
  • Myoglobin
  • NMR
  • Oxygen

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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