AENDO Mar. 39/3

Putman, C. T., M. P. Matsos, E. Hultman, N. L. Jones, and G. J. F. Heigenhauser. Pyruvate dehydrogenase activation in inactive muscle during and after maximal exercise in men. Am. J. Physiol. 276 (Endocrinol. Metab. 39): E483– E488, 1999.—Pyruvate dehydrogenase activity (PDHa) and acetyl-group accumulation were examined in the inactive deltoid muscle in response to maximal leg exercise in men. Seven subjects completed three consecutive 30-s bouts of maximal isokinetic cycling, with 4-min rest intervals between bouts. Biopsies of the deltoid were obtained before exercise, after bouts 1 and 3, and after 15 min of rest recovery. Inactive muscle lactate (LA) and pyruvate (PYR) contents increased more than twofold (P , 0.05) after exercise (bout 3) and remained elevated after 15 min of recovery (P , 0.05). Increased PYR accumulation secondary to LA uptake by the inactive deltoid was associated with greater PDHa, which progressively increased from 0.71 6 0.23 mmol·min21 ·kg wet wt21 at rest to a maximum of 1.83 6 0.30 mmol·min21 ·kg wet wt21 after bout 3 (P , 0.05) and remained elevated after 15 min of recovery (1.63 6 0.24 mmol·min21 ·kg wet wt21; P , 0.05). Acetyl-CoA and acetylcarnitine accumulations were unaltered. Increased PDHa allowed and did not limit the oxidation of LA and PYR in inactive human skeletal muscle after maximal exercise.