Can plasma glucose and nonesterified fatty acid be regulators of glucose utilization in skeletal muscle?

Abstract

The effect of plasma glucose and nonesterified fatty acid (NEFA) on basal and insulin-stimulated glucose utilization in skeletal muscle was assessed by perfused hindlimb preparations. Two-month-old male Wistar rats were divided into four groups: starved, glucose-loaded, hypoglycemic and control. Diabetic rats were made by means of streptozotocin, and divided into three groups: non-treated, insulin-treated normoglycemic and insulin-treated hyperglycemic. The effect of NEFA on glucose clearance was also investigated by adding palmitate to the perfusate. Basal glucose utilization decreased with a rise in plasma glucose concentrations, and increased with a fall in them in each group. The available data strongly support the view that plasma glucose levels play an important role in the control of basal glucose utilization by the hindlimb muscle. In contrast, continuous hyperglycemia in the diabetic state decreased insulin-stimulated glucose utilization by the skeletal muscle, whereas an acute rise in plasma glucose concentrations in the glucose-load state did not. Palmitate stimulated basal glucose utilization, while it decreased insulin-stimulated glucose uptake. It was also clarified that it increased the affinity for glucose in the skeletal muscle in the basal state. This finding seems to indicate that NEFA has some influence on an increase in basal glucose utilization in starvation.