The effect of insulin on glucose metabolism through different pathways and the glucose transporters in Harding-Passey melanoma cells have been studied. Glucose was utilized at a rate of 6.9 ± 2.3 (SD) µmol × g-1 × h-1 with 86% transformed into lactate and pyruvate and only 0.43 and 3% metabolized through the tricarboxylic acid cycle and the pentose phosphate pathway, respectively. Of the total glucose consumed 2% was used in protein synthesis and 2% was used for lipid synthesis. Hexokinase isoenzyme was type I and enolase was present mainly in the αγ hybrid form.

The glucose transporters were cytochalasin B sensitive. The number of high affinity cytochalasin B binding sites was 175,000 receptors/cell (about 0.6 pmol/mg protein) and Kd = 1 × 10-7m. Insulin increased glucose utilization and lactate production by about 70% and caused a 56% increase in transport without alterations in the Kd of the site.

Insulin receptors were quantified by binding assay using 125I-insulin. Kd was 11 × 10-9m with the number of receptors calculated as 11,500/cell. Harding-Passey melanoma cells could thus be a useful model to study basic metabolic events and their modulation by hormones or other effectors.

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This investigation was supported by Research Grant CAICYT 2529/83 from the Spanish Ministry of Education and Science.

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