EFFECT OF NEEDLE-BIOPSY FROM THE VASTUS LATERALIS MUSCLE ON INSULIN-STIMULATED GLUCOSE-METABOLISM IN HUMANS

To examine the cellular mechanisms behind conditions characterized by insulin resistance, the clamp technique is often combined with muscle biopsies. To test whether the trauma of a needle biopsy from the vastu s lateralis muscle per se may influence insulin-stimulated glucose upt ake, eight healthy subjects underwent two randomly sequenced hyperinsu linemic (insulin infusion rate: 0.6 mU.kg(-1).min(-1) for 150 min) eug lycemic clamps with an interval of 4-6 wk. In one study (study B) a mu scle biopsy (approximate to 250 mg, i.e., larger than normal standard) was taken in the basal state just before the clamp procedure, whereas the other was a control study (study C). Insulin-stimulated glucose u ptake was significantly reduced in study B (5.36 +/- 0.96 mg.kg(-1).mi n(-1)) compared with study C (6.06 +/- 0.68 mg.kg(-1).min(-1); P < 0.0 5). Nonoxidative glucose disposal (indirect calorimetry) was decreased (2.81 +/- 1.08 vs. 3.64 +/- 1.34 mg.kg(-1).min(-1); P < 0.05), wherea s glucose oxidation was unaltered. Likewise, endogenous glucose output ([3-H-3]glucose) was identically suppressed during hyperinsulinemia. Circulating levels of epinephrine, glucagon, and growth hormone did no t differ significantly in studies B and C. In contrast, plasma norepin ephrine, serum cortisol, and free fatty acid rose after biopsy (P < 0. 05). In conclusion, performance of a muscle biopsy may diminish insuli n sensitivity by affecting nonoxidative glucose metabolism. This shoul d be considered when assessing whole body insulin sensitivity after a percutaneous needle muscle biopsy.