Effects of Increasing Glucose Concentrations on the Glucose Metabolism in Arterial Tissue and Intestinal Smooth Muscle

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Abstract
The effect of increasing glucose concentrations (0–44.4 mM) on the glucose metabolism in bovine mesenteric arteries and rabbit colon smooth muscle was studied in vitro. The glucose uptake in both these tissues increased when the concentration of glucose in the medium was raised, with saturation at higher glucose concentrations. The rise in glucose uptake was most pronounced in the range 0–11.1 mM. The effect of glucose concentrations on lactate elimination was similar in both tissues to that on glucose uptake. Increases in the tissue levels of glycogen and lactate were observed up to a medium concentration of 5.6–11.1 mM glucose. A further rise in the medium glucose had no effect on the glycogen and lactate contents. In bovine mesenteric arteries the intracellular accumulation of glucose carbon from 14C‐labelled glucose did not change significantly when the glucose concentration was raised from 5.6 to 44.4 mM. The membrane transport of glucose in bovine mesenteric arteries was characterized by saturation kinetics of the Michaelis‐Menten type with a Km of 4.0 mM. These results suggest that the glucose metabolism in bovine mesenteric arteries and rabbit colon smooth muscle is proportionally affected to a greater extent by variations in glucose concentration near the physiological level than by extreme hyperglycemia.