Glucose as a lipolytic agent: studies on isolated rat adipocytes.
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 micromol/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 micromol/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.
Szkudelski
T
T
Department of Animal Physiology and Biochemistry, University of Agriculture, Poznan, Poland. tszkudel@jay.au.poznan.pl
Szkudelska
K
K
D017667:Adipocytes / Q000187:drug effects*; D000818:Animals; D002469:Cell Separation; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D013449:Sulfonamides
D004791:Enzyme Inhibitors; D007328:Insulin; D007546:Isoquinolines; D013449:Sulfonamides; D017868:Cyclic AMP-Dependent Protein Kinases; D005947:Glucose; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D004837:Epinephrine