Glucose as a Lipolytic Agent: Studies on Isolated Rat Adipocytes
T. Szkudelski, K. Szkudelska
Department of Animal Physiology and Biochemistry, University of Agriculture, Poznan, Poland
Received May 4, 1999
Accepted July 21, 1999
Summary
In order to elucidate the direct effect of glucose on lipolysis in isolated rat adipocytes, cells were incubated in a buffer with
different concentrations of this sugar: 2, 8 or 16 mmol/l. The increase in
glucose concentration from 2 mmol/l to 8 or 16 mmol/l enhanced basal lipolysis by 30% and 47 %, respectively. Epinephrine-induced lipolysis (1 m
mol/l) was also increased by 31 % and 32 %, when glucose concentration was
increased from 2 mmol/l to 8 or 16 mmol/l, respectively. The rise in lipolysis
caused by glucose was restricted by H-89 (an inhibitor of protein kinase A, 30
µmol/l), but insulin (1 nmol/l) had no inhibitory action. The augmentation of lipolysis by glucose did not require its metabolism (as demonstrated using
2-deoxyglucose) and was due to the action of this sugar on the final steps of
the lipolytic cascade, particularly on protein kinase A. However, short-term
exposure of adipocytes to higher glucose concentrations did not restrict the
inhibitory action of insulin on lipolysis induced by epinephrine.
Key words
Adipocytes · Glucose · Lipolysis
Reprint requests
T. Szkudelski, Department of Animal Physiology and Biochemistry, University
of Agriculture, Wolynska 35, PL-60-637 Poznan, Poland. e-mail: tszkudel@jay.au.poznan.pl
|