Inhibitory effect of deuterium oxide on glucose oxidation by pancreatic islets

The inhibition of insulin release by deuterium oxide has been interpreted by its stabilizing action on the microtubular system of the beta-cell. Because only indirect information exists about beta-cell metabolism in the presence of D2O, the effect of D2O (99.7%) on glucose oxidation by pancreatic islets was studied. Heavy water reduced 14CO2 formation from [U-14C]glucose (16.7 mM) by ob/ob mouse and rat islets by 50 and 30%, resp. Omission of calcium from H2O-containing media resulted in a 40% diminished glucose oxidation by ob/ob mouse islets. In the absence of calcium, D2O led to a further decrease in 14CO2 production (60%). Erythrocytes oxidized similar amounts of glucose in the absence and presence of D2O. Effects of D2O on glucose transport and mitochondrial respiration are discussed as possible causes of the decreased 14CO2 formation in islet tissue. It is concluded that the inhibition of insulin release by D2O need not necessarily be ascribed to its stabilizing effect on microtubules, but may also be due--at least in part--to the reduction of islet glucose oxidation.