Myoglobin saturation in free-diving weddell seals.
Guyton, Gregory P., Kevin S. Stanek, Robert C. Schneider, Peter W.
Hochachka, William E. Hurford, David G. Zapol, Graham. C. Liggins,
and Warren M. Zapol.
Department of Anaesthesia, Harvard Medical School at Massachusetts,
General Hospital, Boston, MA 02114, Department of Biochemistry,
University of British Columbia, Vancouver, BC Canada, National
Women's Hospital, Auckland, New Zealand
APStracts 2:0241A, 1995.
While the consumption of myoglobin-bound oxygen stores in seal muscles
has been demonstrated in seal muscles during laboratory simulations
of diving, this may not be a feature of normal field diving in which
measurements of heart rate and lactate production show marked
differences from the profound diving response induced by forced
immersion. To evaluate the consumption of muscle MbO2 stores during
unrestrained diving we developed a submersible dual-wavelength laser
near-infrared spectrophotometer capable of measuring myoglobin oxygen
saturation in swimming muscle. The probe was implanted on the surface
of the latissimus dorsi of five subadult male Weddell seals
(Leptonychotes weddelli) released into a captive breathing hole near
Ross Island, Antarctica. Four seals had a monotonic decline of muscle
O2 saturation during free diving to depths of up to 300 m with median
slopes of -5.12 +/- 4.37 % min-1 and -2.54 +/- 1.95 % min-1
respectively for dives lasting < 17 minutes and > 17
minutes. There was no correlation between the power consumed by
swimming and the desaturation rate. Two seals had occasional partial
muscle resaturations late in dives, indicating transfer of O2 from
circulating blood to muscle myoglobin. Weddell seals partially
consume their MbO2 stores during unrestrained free diving.
Received 4 April 1994; accepted in final form 26 April 1995.
APS Manuscript Number A307-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 June 1995.