In VitroInsulin-Stimulated Conversion of [U-14C]Glucose to14CO2by Rat Thymocytes

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Abstract
Addition of bovine insulin to thymocytes from adrenalectomized rats resulted in stimulation of [U-14C]glucose conversion to 14CO2. A significant enhancement of 14CO2 formation by insulin occurred by 30 min of incubation, and was consistently observed at an insulin concentration of 10-8 M. The response to insulin was similar at 0.55 and 1.1 mM glucose, and was obtained at three cell concentrations (0.5, 1.0, 2.0 × 108 cells/ml). The incorporation of [3H]leucine into trichloroacetic acid-precipitable material was significantly increased by 10-6 and 10-8 M insulin. Cycloheximide, at a level of 2.5 × 10-5 M, suppressed [3H]leucine incorporation by 93% and inhibited the stimulation of 14CO2 formation by insulin. We conclude that insulin can enhance the formation of 14CO2 from [U-14C]glucose by thymocytes in vitro, and that this response may require the synthesis of one or more proteins. (Endocrinology102: 751, 1978)