Lm. Perriott et al., Glucose uptake and metabolism by cultured human skeletal muscle cells: rate-limiting steps, AM J P-ENDO, 281(1), 2001, pp. E72-E80
Citations number
30
Categorie Soggetti
Endocrinology, Nutrition & Metabolism
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
To use primary cultures of human skeletal muscle cells to establish defects
in glucose metabolism that underlie clinical insulin resistance, it is nec
essary to define the rate-determining steps in glucose metabolism and to im
prove the insulin response attained in previous studies. We modified experi
mental conditions to achieve an insulin effect on 3-O-methylglucose transpo
rt that was more than twofold over basal. Glucose phosphorylation by hexoki
nase limits glucose metabolism in these cells, because the apparent Michael
is-Menten constant of coupled glucose transport and phosphorylation is inte
rmediate between that of transport and that of the hexokinase and because r
ates of 2-deoxyglucose uptake and phosphorylation are less than those of gl
ucose. The latter reflects a preference of hexokinase for glucose over 2-de
oxyglucose. Cellular NAD(P) H autofluorescence, measured using two-photon e
xcitation microscopy, is both sensitive to insulin and indicative of additi
onal distal control steps in glucose metabolism. Whereas the predominant ef
fect of insulin in human skeletal muscle cells is to enhance glucose transp
ort, phosphorylation, and steps beyond, it also determines the overall rate
of glucose metabolism.