D-glucose metabolism in normal dispersed islet cells and tumoral INS-1 cells

The metabolism of D-glucose was characterized in both normal dispersed rat islet cells and the 2-mercaptoethanol-dependent insulin-secreting cells of the INS-1 line. The normal and tumoral islet cells differed from one anothe r by the relative magnitude, concentration dependency and hierarchy of the increase in the production of (HOH)-H-3 from D-[5-H-3]glucose and C-14-labe lled CO2, acidic metabolites and amino acids from D-[U-C-14]glucose at incr easing concentrations of the hexose. For instance, whilst the paired ratio between D-[U-C-14]glucose oxidation and D-[5-H-3]glucose utilization augmen ted in a typical sigmoidal manner in normal islet cells exposed to increasi ng concentrations of D-glucose, it progressively decreased under the same e xperimental conditions in INS-1 cells. Nevertheless, the absolute values an d concentration-response relationship for the increase in ATP generation ra te attributable to the catabolism of D-glucose were virtually identical in normal and tumoral cells. These findings indicate that the analogy in the s ecretory response to D-glucose of normal and INS-1 islet cells, although co inciding with a comparable response to the hexose in terms of ATP generatio n, contrasts with a vastly different pattern of D-glucose metabolism in the se two cell types.