Abstract
The time course for the effect of insulin on the bovine mesenteric artery, a medium sized artery with a high content of smooth muscle, was studied. The arteries were preincubated for varying times (0-180 min) with and without insulin. The magnitude of the insulin effect, subsequently assayed on the accumulation of glucose carbon and the distribution of 3-0-methylglucose, increased with the time of prior exposure to insulin, approaching a maximum after about 120 min. Insulin exposure also augmented its effect on the incorporation of leucine-14C into protein in a similar way. Preincubation without insulin had no appreciable influence on the magnitude of the insulin effect, indicating that the sensitivity to the hormone did not change with time. The threshold concentration for the effect of insulin on glucose-14C accumulation was 0.01 U/ml without preincubation and 0.001 U/ml after prior exposure to the hormone for 180 min. An action on protein synthesis may be involved in the increase in the magnitude of the insulin effect caused by prior exposure to insulin since no increase was found after inhibition of protein synthesis by puromycin.

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