Erythrocyte changes in canine diabetes mellitus : in vitro effects of hyperglycaemia and ketoacidosis

Diabetes mellitus (DM) is a common metabolic disorder in dogs, which occurs often in association with some complications, including haematological problems. Some abnormalities of erythrocyte metabolism have been described both in human patients and in dogs affected by DM. The aim of this work was to test in vitro the direct effects of hyperglycaemia and ketoacidosis on canine erythrocytes (RBCs). RBCs from healthy dogs were incubated in normoglycaemic, mild hyperglycaemic, severe hyperglycaemic and severe hyperglycaemic + ketoacidotic media. The following parameters were examined: osmotic fragility (OF), the concentrations of 2,3-diphosphoglycerate (2,3DPG), reduced glutathione (GSH) and adenosine triphosphate (ATP), the activities of glutathione peroxidase (GPX), glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase (PK), sodium (Na+) and potassium (K+) intracellular concentrations, production of lactate. In comparison with t0, incubated cells showed higher OF (P <0.001) and lower 2,3DPG (P <0.001) and ATP (P <0.001) concentrations. In comparison with normoglycaemic conditions, hyperglycaemia induced minimal changes, such as increased OF (P <0.001) and 2,3DPG (P <0.01) concentrations. Major changes were induced by hyperglycaemic + ketoacidotic media, such as increases in mean corpuscular volume (MCV), OF, PK activity and ATP concentration; this suggested that oxidative stress had occurred. In hyperglycaemic media, lactate production was not associated with glucose concentration, but the higher consumption of glucose suggests the activation of metabolic pathways other than glycolysis. These alterations could be partly responsible for some hypoxic complications during DM.