AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 2 429-R431, Copyright © 1986 by American Physiological Society
Hematocrit variation during sleep apnea in elephant seal pups
M. A. Castellini, D. P. Costa and A. Huntley
Hematocrit (Hct) levels were found to increase throughout long-duration
sleep apnea in the northern elephant seal pup. Breath holds ranging from 4
to greater than 11 min were sampled. Blood collected from the extradural
intravertebral vein showed an increase in Hct from 55.6 to 63.1% with the
peak value occurring within 1 min of the end of apnea. Plasma lactate did
not change throughout the breath hold. Previous observations of changing
Hct levels in seals were made on animals diving naturally, and consequently
the effects of exercise could not be separated from those of apnea. The
results of this study demonstrate that the rise in Hct is produced quickly
upon apnea, occurs without significant levels of hypoxic metabolism, and
does not depend on exercise.
