Hormonal regulation of glucose transport in a brown adipose cell preparation isolated from rats that shows a large response to insulin.
Isolated brown adipose cells from rats are prepared whose viability is indicated by the expected stimulation of oxygen consumption by noradrenaline and counter-regulation of this oxygen consumption response by insulin. Insulin stimulates 3-O-methyl-D-glucose transport by approx. 15-fold in the absence of adenosine, and adenosine augments this response at least 2-fold. The insulin-stimulated translocation of the glucose transporter GLUT4 from an intracellular compartment to the plasma membrane is readily detected by subcellular fractionation and Western blotting, and the appearance of GLUT4 on the cell surface in response to insulin is demonstrated by bis-mannose photolabelling. Isoprenaline also stimulates glucose transport activity but only by approx. 3-fold; this effect is not altered by adenosine. Isoprenaline increases insulin-stimulated glucose transport activity in the absence of adenosine but decreases it in the presence of adenosine. These results demonstrate that although the regulation of glucose transport by insulin in brown adipose cells is qualitatively similar to that in white adipose cells, counter-regulation by adenosine and isoprenaline is at least quantitatively and may be qualitatively different. Isolated brown adipose cells from rats thus represent an excellent model for further examination of the mechanism by which multiple hormone signalling pathways interact to control glucose transport and GLUT4 subcellular trafficking.
Omatsu-Kanbe
M
M
Experimental Diabetes, Metabolism and Nutrition Section, Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, U.S.A.
Zarnowski
M J
MJ
Cushman
S W
SW
D000241:Adenosine / Q000494:pharmacology*; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D005947:Glucose / Q000493:pharmacokinetics*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D009124:Muscle Proteins; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000378:metabolism
D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495694:Slc2a4 protein, rat; D005947:Glucose; D000241:Adenosine; D007545:Isoproterenol; D009638:Norepinephrine