In vitro and in situ skeletal muscle pyruvate dehydrogenase activity in adrenalectomized and glucocorticoid treated rats.

Skeletal muscle glucose oxidation is significantly reduced and alanine release enhanced in adrenalectomized rats after short-term glucocorticoid treatment. A possible site of regulation is the pyruvate dehydrogenase complex. Pyruvate dehydrogenase activity was measured in vitro in extracts of the gastrocnemius muscle of normal, adrenalectomized and short-term glucocorticoid treated rats by the p-nitroaniline-arylamine-acetyltransferase method and in situ in non-recirculating perfusions of isolated hindlimbs with physiological pyruvate levels and tracer doses of [1-14C] pyruvate by measuring the off-kinetic of 14CO2 wash out in the effluent. Neither method showed a direct influence of glucocorticoids on skeletal muscle pyruvate dehydrogenase activity.