title: Adipocyte glycogen synthase and pyruvate dehydrogenase in obese and type II diabetic subjects.
abstract: To determine whether 1) insulin stimulates pyruvate dehydrogenase (PDH) and glycogen synthase (GS) in isolated human adipocytes and 2) adipocytes from subjects with obesity or noninsulin-dependent diabetes mellitus (NIDDM) are resistant to the effects of insulin, PDH and GS were assayed in adipocytes from 11 control, 8 obese, and 9 NIDDM subjects. Basal PDH activities were 123 +/- 20, 129 +/- 21, and 128 +/- 25 pmol pyruvate oxidized/min per 2 X 10(5) adipocytes in these groups. Insulin stimulated PDH activity to a maximum of 223 +/- 38 pmol/min per 2 X 10(5) in adipocytes from control subjects, but did not significantly increase values from obese subjects. Insulin significantly decreased PDH activity in cells from NIDDM subjects (99 +/- 20 pmol/min per 2 X 10(5) cells, P less than 0.05). PDH activity assayed with high magnesium and calcium concentrations was significantly stimulated by insulin in adipocytes from control, but not obese or NIDDM subjects. GS assayed with 1 mM glucose 6-phosphate did not differ significantly among control, obese, or NIDDM subjects (446 +/- 110, 451 +/- 156, and 291 +/- 35 pmol incorporated into glycogen, respectively). Insulin significantly stimulated glycogen synthase in all three groups (827 +/- 179, 764 +/- 177, and 569 +/- 51 pmol incorporated) to a similar extent. Glycogen synthase assayed with 10 mM glucose 6-phosphate was decreased in NIDDM (1,335 +/- 131 pmol incorporated) compared with obese or control subjects (2,512 +/- 451 and 2,239 +/- 230 pmol incorporated, respectively, P less than 0.01).
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology*; D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology*; D005260:Female; D006006:Glycogen Synthase / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000201:enzymology*; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism*
chemical_list: D007328:Insulin; D011768:Pyruvate Dehydrogenase Complex; D006006:Glycogen Synthase