[The effects of insulin and glucose on the utilization of non-esterified fatty acid in the resting rat skeletal muscle].

The present study was undertaken to clarify the effects of insulin and glucose on the utilization of non-esterified fatty acid (NEFA) in the resting rat skeletal muscle using the perfusion technique. The 24hr-starved and non-starved rat hind limbs were perfused for one hour with the perfusion mediums containing 1mM palmitate and various concentrations of glucose and insulin, and sampling was performed to calculate the clearance of NEFA (F value). In the absence of glucose, the F value of the starved rat hind limb was less than that of the non-starved rats, independently of insulin concentrations (0 and 125 microU/ml) in the perfusion medium (p < 0.02). Moreover, there was no influence of insulin on the F value in both the starved and the non-starved groups. In the presence of 13.9mM glucose, there were no statistically significant differences in the F value without insulin between the non-starved and starved groups. However, the F value was increased in the presence of 62.5 or 125 microU/ml insulin, compared with that in the absence of insulin (p < 0.001), although when the insulin concentration was elevated to 500 microU/ml, it was decreased. Both in the non-starved and the starved groups independently of insulin concentrations, the F value in the glucose-added condition was increased, compared with that in the absence of glucose. These results indicated that the utilization of NEFA in the resting rat skeletal muscle was facilitated by the moderate supply of glucose, although it was suppressed by the presence of abundant glucose.