Animals display a variety of biological reactions to the external stress to maintain
homeostasis. Hans Selye defined the stress as nonspecific respnse to a variety of noxious
stimuli, and is charactered by three stage, first is alarm, second is resistance, and third is
exhaustion. In the stage of alarm sympathetic nerve system and parasympathetic nerve
system act together in secretion of biological fluids.
It is well known that when we get stress, nerve signal transmited to the adrenal cortex and
adrenal medulla from brain, and epinephrine, norepinephrine, and cortisol are secreted.
Authors tried to investigate the variation of catecholamine and mineral excretion from urine
under the cold environment by using rat. Rats were kept in the 5℃environment for 1, 3, 6,
and 12 hours and then the 24 hours urine were taken in the rat metabolize cage. The
catecholamine was extracted with alumina method and analyzed by HPLC-ECD and got the
following results.
In the normal rat urine, the amount of norepinephrine excretion was 0.571 ng/ml and the
epinephrine was 0.351 ng/ml, and dopamine was 0.571 ng/ml. But in the cold stressed group
for 1 hour, the amount of norepinephrine excretion was increased to 0.733 ng/ml and in the 3
hour group the amount was also increased to 0.863 ng/ml, in 6 hours group 1.068 ng/ml, and
in the 12 hour group the epinephrine excretion amount was 0.985 ng/ml.
The amount of epinephrine excretion was also increased in accordance with the exposure
time. In the 1 hour exposed group the excretion amount was 0.460 ng.ml, in 3 hour 0.578
ng/ml, in 6 hour 0.685 ng/ml, in 12 hour exposure the amount was 0.711 ng/ml. The
dopamine was not increased regardless of the duration of exposure time unlike other two
catecholamines.
The amount of Ca excretion was increased twice after 1 hour exposure to 5℃ cold
temperature, but Mg didn't show great difference through cold stress experiments.
Through the above experiments author recognized that there were relationship between cold
stress and catecholamine excretion, Ca was also could be a early indicator of the cold stress.
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