D-xylose transport in isolated skeletal muscle of chickens: Effects of insulin and tolbutamide

Abstract

1. Cellular uptake of sugar by an incubated avian skeletal muscle (M. extensor metacarpi radialis) was estimated by measuring the uptake of D-[U- 14C]xylose. 2. Xylose uptake (1–14 μmol/g/hr) and the time courses for penetration of the muscles by xylose and by the extracellular marker D_[1- 3H]-sorbital, were similar to those reported for mammalian muscles 3. Bovine insulin produced modest increases (usually <50%) in xylose uptake and was effective at a concentration in the medium (500 μU/ml)-lower than in most earlier in vitro studies of avian muscles. 4. Tolbutamide (0.5–2 mg/ml) caused similar increases in xylose uptake, both in the presence and absence of exogenous insulin. 5. The results provide further evidence for a direct extrapancreatic action of tolbutamide on avian muscle.