RELATIONSHIP BETWEEN INSULIN-MEDIATED GLUCOSE DISPOSAL AND REGULATIONOF PLASMA AND ADIPOSE-TISSUE LIPOPROTEIN-LIPASE

The relationship between insulin-mediated glucose disposal and fasting insulin and triglyceride (TG) concentrations, plasma post-heparin lip oprotein lipase (PH-LPL) activity and mass, and adipose tissue LPL act ivity, mass, and mRNA content was defined in 19 non-diabetic men. Insu lin-mediated glucose uptake [as assessed by determining the steady-sta te plasma glucose (SSPG) concentration during a continuous infusion of somatostatin, insulin, and glucose] was significantly correlated with fasting TG concentration (r = 0.54, p < 0.02), plasma PH-LPL activity (r = -0.52, p < 0.03) and mass (r = -0.49, p < 0.03), and adipose tis sue LPL mRNA content (p = -0.68, p < 0.001). Comparable relationships were also seen when fasting insulin concentration was substituted for SSPG. Although adipose tissue LPL and mass correlated with each other (r = 0.76, p < 0.001) in a fasting state, they were not related to any other variable measured. Using in vivo and molecular biology techniqu es, these data demonstrate that the more insulin resistant an individu al, the lower the level of plasma PH-LPL activity and mass, and the hi gher the plasma TG concentration. Since lower concentrations of adipos e tissue mRNA were also directly correlated with plasma PPI-LPL mass ( r = 0.57, p < 0.01), and inversely with plasma TG concentration (r = - 0.68, p < 0.001) as well as SSPG (r = -0.68, p < 0.001), it can be pos tulated that the relationship between insulin resistance and LPL activ ity and plasma TG concentration is associated with the inability of in sulin to stimulate the transcription or to increase the intracellular mRNA stability of adipose tissue LPL in insulin resistant individuals.