from the perfused pancreas as well as from isolated islets are required to clarify this point.
The significant increase in the evolution of respiratory '*CO* by the animals treated with cadmium indicates that multiple dosages of cadmium alter carbohydrate metabolism. The affected mechanisms may involve glycolysis, the tricarboxylic acid cycle, respiration, or a combination of these. It was reported (15-17) that cadmium ions uncouple oxidative phosphorylation. This uncoupling may be due to the effect of cadmium on the transport of ions across the mitochondria1 membrane (16) or to the blocking of some free active site (15). Uncoupling oxidative phosphorylation increases the adenosine diphosphate concentration relative to that of adenosine triphosphate. This causes an increase in the rate of glycolysis and the tricarboxylic acid cycle since it activates certain enzymes such as phosphorylase a, adenosine triphosphate:o-fructose 6-phosphate 1-phosphotransferase, adenosine triph0sphate:pyruvate phosphokinase, and isocitrate dehydrogenase.
With the increase in the rates of glycolysis and the tricarboxylic acid cycle after cadmium treatment, there may be a concomitant increase in labeled glucose utilization. With the information available, it is not possible to explain further the effect of cadmium on the evolution of carbon dioxide in vivo and further work is indicated.