AJP - Endocrinology and Metabolism, Vol 263, Issue 3 E570-E574, Copyright © 1992 by American Physiological Society
Plasma carnitine in fasting neonatal and adult northern elephant seals
S. H. Adams, D. P. Costa and S. C. Winter
Marine Sciences Department, University of California, Santa Cruz 95064.
Maintenance of adequate body carnitine stores is a requisite for fasting
mammals, whose energy is derived mainly from free fatty acid oxidation. The
impact of longterm fasting on carnitine status is unclear, and there have
been no reports of carnitine during naturally occurring fasts. Total (TC),
free (FC), and acylated (AC) plasma carnitine levels were determined in 10
weaned and 11 adult northern elephant seals (Mirounga angustirostris)
during natural fasts lasting from 1 to 3 mo. In pups, TC declined little
and AC increased only slightly [P greater than 0.05, analysis of variance
(ANOVA)] through 11 wk of fasting. Plasma FC dropped by 53 and 26% from
week 1 values at 10 and 11 wk fasting, respectively (P = 0.014, ANOVA). The
AC/FC ratio did not approach 1.0 until 7 wk of fasting. TC was 38.6 +/- 1.4
microM and 47.6 +/- 4.1 microM in adult females and males, respectively.
Adult AC/FC ratios were 0.71 +/- 0.10 (females) and 0.08 +/- 0.04 (males).
Plasma TC status is not negatively affected by extended fasting in adult
and weaned northern elephant seals. These data support the hypothesis that
fasting northern elephant seals defend plasma TC and maintain an attenuated
AC/FC ratio well into their prolonged natural fast.
