Glucose-6-phosphate dehydrogenase activity in erythrocytes from chronically copper-poisoned sheep

The present study was undertaken to investigate the capacity to generate reducing equivalents in erythrocytes from experimentally copper-poisoned sheep. Ten ewes were dosed orally with CuSO4 to induce the Cu toxicity. Copper dosing was stopped at the first day of hemolysis. The activity of glucose-6-phosphate dehydrogenase (G6PD) in the erythrocytes, the levels of reduced glutathione (GSH) and glucose (in serum and erythrocytes) was examined at frequent intervals. The copper-poisoned sheep had reduced levels (25-35% less) of glucose in serum and erythrocytes than controls. The activity of G6PD in erythrocytes from sheep was 50-60% of typical levels found in human erythrocytes. Immediately before the hemolytic period, the copper-poisoned sheep showed decreased activity of G6PD, declining to 65% of the initial activity. In addition, we found decreased blood levels of reduced GSH in copper-poisoned sheep. There appears to be a relationship between decreased capacity to generate reducing equivalents and the overload of copper in sheep erythrocytes.