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Made in the Undted, States of ArneilcaRepriuted from JounNlr oF
MaMMALocyVol. 38, No. 3, Augmt, 1957pp.423424August,1957 GENI'RAL
NOTES
SERUM MAGNESIUM CHANGES IN COLD.EXPOSED MAMMALSHibernation and
hypothermia have been subjects of increasing interest in recent
years, yetthere is a dearth of observations on the biochemistry of
these states. High levels of mag-nesium in serum have been related
by several investigators to hibernation and cold ex-posurel,2,a. fn
the present studies an active dse in the serum level of magnesium
was foundwith hibernation or winter rest in three orders of
mammals, Serum magnesium and hematolo-
gical data were obtained on two species of bats, thirteen-lined
ground squirrels and goldenhamsters, and the black bear.
Hibernating and non-hibemating conditions were included.Magnesium
levels as determined by the method of Orange and Rheina were
observed to beconsistently higher during hibernation than in active
animals. The percentage increase inthe serum magnesium varied with
the species studied: little brown bat, Mgotis lucifugus, 62per
cent; big brown bat, Eptesicus fuscvs,53 per cent; thirteenlined
ground squirrel, Citellustridecemlineatus,65 per cent; golden
hamster, Mesocricetus auratus,25 per cent; and blackbear, Ursus
ameNcanus, in winter rest, 29 per cent. The mean values in
milligrams per onehundred milliliters of serum, for active and
hibernating animals respectively, are given inTable 1. In contrast
to these changes indicated above, cold exposure without hibernation
orwinter rest did not elevate the serum magnesium. The serum
specific gravity and bloodhematocrit occasionally increased with
hibernation, but not consistently, thereby indicatingthe rise in
the serum magnesium to be an active process.
423
1 Suomalaiqen, P., Ann. Acad. Sci, Fennicae, A, 53, I
(1939),2Platner, W. w., md M. J. Hosko, Aner. Jour. Phvsioi.,
174,273 (f953),^_e M_cBirnie,X, E,, F, G. Pearson, G. A. Truier, H.
H. Karachi and W. G. Bigelow, Canad. Jour, Med. Sci.,3r,42r
(1935).aOrange, M., and H. C. Rhein, Jou. Biol. Chem., 189, 379
(f951).
7/29/2019 SERUM MAGNESIUM CHANGES IN COLD-EXPOSED MAMMALS
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424 JOURNAL OF MAMMALOGY Vol.3& No. 3Some of the details of
the change in serum magnesium were determined using little
brownbats. The elevation of serum magnesium occurred after only one
to two hours of hibernationand was found by the time the esophageal
temperature had dropped to 13" C, There was nosignificant serum
magnesium increase when esophageal temperature had dropped to
only17" C, Awakening from hibernation does not require a lowering
of the serum magnesium
since there was no reduction of serum magnesium when body
temperature was raised to 18' C.One hour after arousal from
hibernation the serum magnesium had dropped to the level tlpi-cal
of active animals.
T.xw.n L-Serunx nagnesi,urn letsels in hibernatinn and uinter
rest(All values are milligrams per one hundred milliliters of
serum. )
7.32 6.050.60 0.3164
4.03 3.810.10 0.2r22
5.01 4.850.072l
3.2 2.80.464
6.0 4.40.314
This research was made possible by a grant from the National
Science Foundation. Someof the animals were obtained with the kind
assistance of Dr. Glen C. Sanderson of the IowaState Department of
Conservation. The serum of the black bears was obtained with
obviousdifficulty by Dr, Raymond J. Hock and sent packed in ice
from the Arctic Health ResearchCenter, Anchorage, Alaska. The
details of tlis investigation will be published in separateaccounts
elsewhere, but the combined data presented here indicate that
elevated serum mag-nesium may be as characteristic of hibernation
as lowered body temperature and metabolism.-M. L. Rrnorspr- eNn G.
E, For,r, JR., Dept. of Occupatdonal Health, Unio. of
Pittsburgh,Pi,ttsbu.rgh, Pa. and Dept of Phgsiologg, State Unio. of
lowa, Iowa Citg. Receioed August 73,I956.
II Uttfe I Big brown llined groudl Golden I Black I Hedgehog
lWoodcbuckI brown bat lbat (a dars)l squinel I hamster I ueu I
tnet. r) | {ner. e)MagnesiumMean ---------- 4.38Std. dev. ------
0.16No. deter. ---- 36
(2 days)MagnesiumMean ---------- 7.LlStd. dev. ------ 0.13No.
deter. ---- 15
Actioe4.78 3.650.61 0.41108
Hiberrwtine(2days) (2days) (2days) (1mo.)Inactive
