| Abstract: | An incubation of uremic human serum with normal rat adipose tissue will make the subsequently isolated adipocytes less responsive to insulin. To examine the extent of insulin resistance, we obtained sera from nondiabetic, uremic patients, who had not undergone dialysis therapy. The sera were then dialyzed (3500 molecular-weight cutoff) for 18 hr against a defined culture medium to eliminate possible in vitro effects of altered levels of end-product metabolites, electrolytes, and metabolic substrates. After an incubation of epididymal fat tissue from normal rats, for 3 hr with the dialyzed sera (50% vol/vol), cells were isolated and washed. The insulin stimulation of 14C-glucose (0.2 mM) incorporation to 14CO2 and total lipids was significantly reduced in the adipocytes pretreated with sera from 19 of the 29 uremic patients. Although elevated in the uremic patients, the sera levels of insulin, and parathyroid and growth hormones were not correlated to insulin resistant activity. Furthermore, incubation of adipose tissue for 3 hr with insulin, glucagon, or PTH did not produce resistance. The uremic sera reduced glucose utilization equally at 0.2 and 50 mM glucose, suggesting that the insulin resistance was induced additionally at a site distal to the glucose transport system. However, the concentration of insulin (22 microunits/ml) required for half-maximal stimulation of glucose metabolism was not altered by pretreatment with uremic serum. Also, neither the isoproterenol-stimulated lipolysis nor the inhibition of this cellular event was influenced by pretreatment with uremic sera.(ABSTRACT TRUNCATED AT 250 WORDS) |
