Hh. Klein et al., Insulin activation of insulin receptor kinase in erythrocytes is not altered in non-insulin-dependent diabetes and not influenced by hyperglycemia, J ENDOCR, 166(2), 2000, pp. 275-281
Recent studies suggest that high glucose concentrations impair insulin rece
ptor phosphorylation and kinase activation in certain cell models. To exami
ne whether such an effect of glucose call also be demonstrated in vivo, ins
ulin receptor kinase activation was studied in erythrocytes from 11 patient
s with non-insulin-dependent diabetes (NIDDM), before and after reduction o
f hyperglycemia (from 14.6 +/- 1.6 to 6.6 +/- 0.5 nmol/l fasting plasma glu
cose within 8.6 +/- 0.6 days). For the measurement of receptor kinase activ
ation, cells were incubated with insulin (0-400 nmol/l), solubilized and in
sulin receptors immobilized to microwells coated with antiinsulin receptor
antibody. Kinase activity towards insulin receptor substrate-1 and insulin
binding were then measured in these wells. Kinase activities (expressed as
amol phosphate transferred per min and per fmol insulin binding activity) w
ere similar before (2.4 +/- 0.4 and 32.2 +/- 2.0 amol/min per fmol with 0 a
nd 400 nmol/l insulin, respectively) and after improvement of metabolic con
trol (2.4 +/- 0.5 and 32.0 +/- 2.3 amol/min per fmol with 0 and 400 nmol/l
insulin, respectively). Moreover, activities were also similar in 22 hyperg
lycemic patients with NIDDM (2.1 +/- 0.3 and 35.1 +/- 1.4 amol/min per fmol
with 0 and 400 nmol/l insulin, respectively) compared with those in 21 non
-diabetic control individuals (2.1 +/- 0.3 and 34.2 +/- 1.2 amol/min per fm
ol with 0 and 400 nmol/l insulin, respectively). We conclude that insulin a
ctivation of erythrocyte insulin receptor kinase is not impaired in NIDDM a
nd is not influenced by hyperglycemia.