La. Nolte et al., HYPERGLYCEMIA ACTIVATES GLUCOSE-TRANSPORT IN RAT SKELETAL-MUSCLE VIA A CA2-DEPENDENT MECHANISM(), Diabetes, 44(11), 1995, pp. 1345-1348
Citations number
24
Categorie Soggetti
Endocrynology & Metabolism","Medicine, General & Internal
We investigated the acute effect of hyperglycemia on 3-O-methylglucose
transport in isolated rat epitrochlearis muscles, High levels of gluc
ose (20 mmol/l) induced an approximately twofold increase in the rate
of glucose transport when compared with muscles exposed to a low level
of glucose (8 mmol/l) (P < 0.001), The hyperglycemic effect was addit
ive to the effects of both insulin and exercise on the glucose transpo
rt rates, Dantrolene (25 mu mol/l), a potent inhibitor of Ca2+ release
from the sarcoplasmic reticulum, blocked the ability of hyperglycemia
to increase glucose transport by 73% (P < 0.01), Although dantrolene
had no effect on the non-insulin-stimulated or the insulin-stimulated
glucose transport rates during normoglycemic conditions, the effect of
exercise was completely blocked in the presence of dantrolene (P < 0.
01), Inhibition of phosphatidylinositol (PI) 3-kinase by wortmannin (5
00 mmol/l) had no effect on the activation of glucose transport by hyp
erglycemia, whereas the insulin-stimulated glucose transport was compl
etely abolished (P < 0.001), These findings suggest that hyperglycemia
activates glucose transport by a Ca2+ dependent pathway, The signalin
g system for this Ca2+ dependent activation of glucose transport does
not involve the activation of PI 3-kinase and is separate from the mas
s-action effect of glucose on glucose transport.