Less of insulin desensitization in sympathetic nerve terminals from Wistarrats with insulin resistance

In an attempt to determine the effect of hyperinsulinemia on sympathetic fu nction, release of norepinephrine (NE from isolated aorta by insulin was me asured in Wistar rats with insulin resistance. Insulin resistance was produ ced when the hypoglycemic action of glibenclamide at a dose of 10 mg/kg was almost abolished in rats that received daily injections of long-acting ins ulin for 15 days. Moreover, the stimulatory effect of insulin on glucose up take was markedly reduced in both skeletal muscle strips and white adipocyt es obtained from these rats with insulin resistance. However, the stimulato ry effects of insulin at concentrations from 5 to 15 U/l on the release of NE from the aortic strip of insulin-resistant rats were not modified in the same manner but only slightly reduced compared with that of normal rats. T hese results suggest that insulin desensitization was produced later in sym pathetic nerve terminals than in other organs in insulin-resistant rats and this may be helpful to explain the sympathetic hyperactivity associated wi th diabetes in clinics. (C) 2000 Elsevier Science B.V. All rights reserved.