Glucose metabolism in isolated brown adipocytes under beta-adrenergic stimulation. Quantitative contribution of glucose to total thermogenesis.
To quantify the potential of brown adipose tissue as a target organ for glucose oxidation, O2 consumption and glucose metabolism in isolated rat brown adipocytes were measured in the presence and absence of insulin, by using the beta-agonists isoprenaline or Ro 16-8714 to stimulate thermogenesis. Basal metabolic rate (278 mumol of O2/h per g of lipid) was maximally stimulated with isoprenaline (20 nm) and Ro 16-8714 (20 microM) to 1633 and 1024 mumol of O2/h per g respectively, whereas insulin had no effect on O2 consumption. Total glucose uptake, derived from the sum of [U-14C]glucose incorporation into CO2 and total lipids and lactate release, was enhanced with insulin. Isoprenaline and Ro 16-8714 had no effect on insulin-induced glucose uptake, but promoted glucose oxidation while inhibiting insulin-dependent lipogenesis and lactate production. A maximal value for glucose oxidation was obtained under the combined action of Ro 16-8714 and insulin, which corresponded to an equivalent of 165 mumol of O2/h per g of lipid. This makes it clear that glucose is a minor substrate for isolated brown adipocytes, fuelling thermogenesis by a maximum of 16%.
Isler
D
D
Department of Pharmaceutical Research, F. Hoffmann-La Roche and Co., Basle, Switzerland.
Hill
H P
HP
Meier
M K
MK
D015078:2-Hydroxyphenethylamine / Q000031:analogs & derivatives / Q000494:pharmacology*; D002001:Adipose Tissue, Brown / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects; D005227:Fatty Acids / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D050356:Lipid Metabolism; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D010627:Phenethylamines / Q000494:pharmacology*; D051381:Rats
D005227:Fatty Acids; D007328:Insulin; D010627:Phenethylamines; D015078:2-Hydroxyphenethylamine; C045606:4-(3-(bis(beta-hydroxyphenethyl)amino)butyl)benzamide; D005947:Glucose; D007545:Isoproterenol