Insulin-resistant Na+ pump activity in adipocytes from obese humans.
Basal and maximally insulin-stimulated Na+-pump activity was measured in adipocytes from subjects with normal glucose tolerance over a range of body mass indexes (BMI). In a comparison of 13 lean (BMI less than 25) vs. 15 extremely obese (BMI greater than 40) subjects basal activities per unit surface area were similar, but the maximally insulin-stimulated activity was significantly reduced in the extremely obese group [9.2 +/- 0.6 vs. 12.1 +/- 1.0 (min X dam2)-1, P less than 0.05]. The mean percent insulin stimulation of the Na+ pump above basal activity was 48 +/- 7% for the lean compared with 14 +/- 2% for the extremely obese group (P less than 0.001). A similar relationship was observed in these subjects for glucose transport where basal activities per unit surface area again were similar but the maximally insulin-stimulated transport was reduced in the extremely obese subjects (2.2 +/- 0.3 vs 5.1 +/- 0.6 attol/um2 X s, P less than 0.001). These results indicate that alterations in Na+-pump activity may be a manifestation of the insulin-resistant state that could contribute to the development of obesity via decreased cellular thermogenesis.
D M
DM
Mott
R L
RL
Clark
W J
WJ
Andrews
J E
JE
Foley
D000273:Adipose Tissue / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007198:Indians, North American; D007333:Insulin Resistance; D007473:Ion Channels / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011868:Radioisotopes; D012413:Rubidium; D012964:Sodium / Q000378:metabolism*; D044465:White People
D007473:Ion Channels; D011868:Radioisotopes; D010042:Ouabain; D012964:Sodium; D005947:Glucose; D012413:Rubidium