AJP - Endocrinology and Metabolism, Vol 256, Issue 1 E179-E185, Copyright © 1989 by American Physiological Society
Discrepancy between glucose transport and transporters in human femoral adipocytes
E. Karnieli, R. Moscona, R. Rafaeloff, Y. G. Illouz and M. Armoni
Department of Medicine C, Rambam Medical Center, Haifa, Israel.
Obesity is known to be associated with insulin resistance in human and rat
adipocytes. However, it is not known what are the perturbations in insulin
action that contribute to disproportional femoral obesity. Thus femoral
subcutaneous adipose tissue was obtained from lean women with various
degrees of disproportional obesity, by liposuction. 3-O-methylglucose
(3-O-methyl-D-glucopyranose) transport was measured in intact cells, and
glucose transporter levels in plasma and low-density microsomal membranes
were assessed using the cytochalasin B binding assay. A sixfold cellular
enlargement was associated with increase in both basal and
insulin-stimulated glucose transport activity in the intact cell, and a
300-600% increase in insulin stimulating effect per se. However, when
glucose transporter levels were assessed, this cellular enlargement was
accompanied by a 40-70% transporter depletion (in largest cells compared
with smallest ones) in both subcellular fractions examined, from either
basal or insulin-stimulated cells. This discrepancy, between increasing
cellular glucose transport rates and relative depletion of transporter
levels, suggests that these cells are not insulin resistant, as could be
expected from their large size. A role for other factor(s), additional to
glucose transporter levels, in the regulation of cellular glucose uptake
rate is thus suggested.
