EXERCISE INDUCES HUMAN LIPOPROTEIN-LIPASE GENE-EXPRESSION IN SKELETAL-MUSCLE BUT NOT ADIPOSE-TISSUE

Lipoprotein lipase (LPL) is regulated by exercise in humans, but the e ffects of exercise on LPL expression in different tissues and the mole cular mechanisms involved are unclear. We assessed the effects of 5-13 consecutive days of supervised exercise on tissue LPL expression as w ell as fasting plasma lipids and lipoproteins in 32 sedentary, weight- stable adult men. In skeletal muscle, exercise training increased the mean LPL mRNA level by 117% (P = 0.037), LPL protein mass by 53% (P = 0.038), and total LPL enzyme activity by 35% (P = 0.025). In adipose t issue, mean LPL mRNA, protein mass, and activity did not change. Exerc ise decreased triglycerides [from 172 +/- 4.3 to 127 +/- 3.2 (SE) mg/d l, P = 0.002], total cholesterol (from 188 +/- 1.2 to 181 +/- 1.0 mg/d l, P = 0.011), and very low-density lipoprotein-cholesterol (from 30.1 +/- 0.9 to 22.0 +/- 0.8, P = 0.004) and increased high-density lipopr otein cholesterol (HDL-C; from 43.4 +/- 0.35 to 45.0 +/- 0.37, P = 0.0 30) and HDL(2)-C (from 6.6 +/- 0.21 to 7.7 +/- 0.19, P = 0.021). Chang es in muscle but not adipose tissue heparin-releasable LPL activity we re inversely correlated (r = -0.435, P < 0.034) with changes in trigly cerides. These data suggest the existence of an exercise stimulus intr insic to skeletal muscle, which raises LPL activity in part by pretran slational mechanisms, a process that contributes to the improvement in circulating lipids seen with physical activity.