Effect of
Hypothermia on Insulin - Receptor Interaction
in Different Rat Tissues
T.
TORLINSKA, M. PERZ, E. MADRY, T. HRYNIEWIECKI,
K.W. NOWAK1,
P. MACKOWIAK1
Department
of Physiology, University School of Medical
Sciences, and 1Department
of Animal Physiology and Biochemistry, University
of Agriculture, Poznan, Poland
Received November 6, 2000
Accepted December 17, 2001
Summary
Experimental hypothermia caused
extensive changes in the number of both classes
of insulin receptors in different rat tissues. In
the liver, the number of high affinity insulin
receptors (HAIRs) decreased by 50 % (from 25.3 to
12.6 fmol/mg membrane protein), whereas number of
low affinity insulin receptors (LAIRs) was almost
unchanged in comparison to normothermic animals
(5.63 and 4.39 pmol/mg, respectively). In the
adipose tissue, number of both classes was
reduced - HAIRs by 81 % (from 24.0 to 4.50
fmol/mg) and LAIRs by 92 % (from 16.0 to 1.29
pmol/mg). In the skeletal muscle, capacity of
HAIRs was not changed (16.2 and 19.3 fmol/mg in
normo- and hypothermic animals, respectively),
whereas number of LAIRs increased by 150 % (from
6.65 to 16.6 pmol/mg). Hypothermic rats also
showed lower amount (by 85 %) of LAIRs in the
heart muscle (9.37 and 1.43 pmol/mg in control
and experimental animals, respectively).
Simultaneously, no significant changes were found
in HAIRs (16.3 and 11.9 fmol/mg, respectively)
and LAIRs (4.43 and 3.88 pmol/mg, respectively)
in the brain. These differences in insulin
receptors responses to hypothermia may reflect
different physiological role of insulin in the
regulation of target cell metabolism and/or the
differences in tissue distribution of the insulin
receptor isoforms.
.
Key
words
Hypothermia
· Insulin receptors · Liver · Adipose tissue
· Skeletal muscle · Heart · Brain
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T. Torlińska, Department of Physiology,
University of Medical Sciences, Świecickiego 6,
60-781 Poznań, Poland
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