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First published online October 7, 2008
Journal of Experimental Biology 211, 3323-3332 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.018887
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Blood flow and metabolic regulation in seal muscle during apnea

Paul J. Ponganis1, Ulrike Kreutzer2, Torre K. Stockard1, Ping-Chang Lin2, Napapon Sailasuta3, Tuan-Khan Tran2, Ralph Hurd3 and Thomas Jue2,*

1 Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
2 Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA 95616, USA
3 GE Medical Systems, Fremont, CA 94539, USA

* Author for correspondence (e-mail: TJue{at}ucdavis.edu)

Accepted 19 August 2008

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 4.5x10–7 cm2 s–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.

Key words: Doppler, muscle, myoglobin, NMR, oxygen, hemodynamics


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Related articles in JEB:

HOW SEALS MANAGE THEIR INTERNAL SCUBA TANK
Kathryn Phillips
JEB 2008 211: ii. [Full Text]  



This article has been cited by other articles:


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J. Exp. Biol., October 15, 2008; 211(20): ii - ii.
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