Stimulatory Effect of Insulin on Glucose Metabolism of Thymus Lymphocytes[*]

Abstract

The effect of insulin and cortisol on glucose metabolism of thymus lymphocytes from adrenalectomized rats was studied. The addition of 10^-8 M insulin increased glucose uptake, lactate production and the production of ¹⁴CO₂ from labeled glucose at an initial concentration of 1.1 mM. Insulin stimulation of glucose metabolism was antagonized by 10^-6 M Cortisol, which inhibited glucose metabolism with or without insulin present.

At a glucose substrate concentration of 11 mM, it was not technically possible to measure glucose uptake, but the presence of 10^-8 M insulin increased lactate production 32% and caused a small but statistically significant increase in glycogen content. As with the lower substrate concentration, 10^-8 M cortisol opposed the effects of insulin by decreasing both lactate production and glycogen content of the cells. It may be concluded that thymus lymphocytes can display insulin sensitivity under physiologic conditions.

Key words

Insulin - Cortisol - Glucose Metabolism - Thymus Lymphocytes - Glycogen

1 This work was supported by US Public Health Service Research Grant CA10291 from the National Cancer Institute. The studies reported were taken from a thesis submitted to the Univ. of Nebraska in partial fulfillment of the requirements for the Ph.D. degree.

1 This work was supported by US Public Health Service Research Grant CA10291 from the National Cancer Institute. The studies reported were taken from a thesis submitted to the Univ. of Nebraska in partial fulfillment of the requirements for the Ph.D. degree.

2 Present address: Department of Biochemistry, University of Oregon Medical School, Portland, Oregon, USA.