Erythrocyte metabolism in healthy dogs and preliminary results in cardiopathic and anaemic dogs

ERYTHROCYTE METABOLISM IN HEALTHY DOGS AND PRELIMINARY RESULTS IN CARDIOPATHIC AND ANAEMIC DOGS Paltrinieri S., Agnes F., Sartorelli P. Istituto di Patologia Generale Veterinaria - Milano - Italy Glycolysis plays a central role in red cell preservation by producing energy and reducing compounds to prevent oxidative membrane damage. Erythrocyte metabolism might be stressed in diseases involving oxygen transport. To compare biochemical differences between the red cells of diseased dogs and control dogs, pyruvate-kinase (PK), glucose-6-phosphate-dehydrogenase (G6PDH) and 2,3 diphosphoglycerate (2,3DPG) levels were investigated in 10 healthy dogs (Group 1), in dogs with subclinical dirofilariosis (Group 2, n=5), moderate heart diseases (Group 3, n=5), severe heart failure (Group 4, n=6) and haemolytic anaemia (Group 5, n=3). PK and G6PDH are important in the glycolytic pathway in which ATP and NADPH are produced, while 2,3DPG is known to upregulate the haemoglobin dissociation curve. They are reported to increase in man with increased oxygen need. In addition the erythrocyte osmotic resistance was measured to evaluate red cell aging and/or membrane preservation. In group 1, no haematological abnormalities were found. The baseline values of PK (2.1 ± 1.3 mU/g Hb) G6PDH (2.3 ± 1 mU/g Hb) and 2,3DPG (15 ± 1.2 mol/g Hb) agreed with those reported by Jain (1) and Chapman and Giger (2). The dogs of group 2 and 3 also, did not show haematological or metabolic alterations. Severe anaemia and neutrophilic leukocytosis were found in the dogs from group 5 (P<0.001) and, to a lesser degree, in group 4. Anaemic dogs had the higher values of PK (23.5 ± 15.7, P<0.001), G6PDH (6.1 ± 0.9) and 2,3DPG levels (21.8 ± 8.2, P<0.001) followed by those of group 4 (10.6 ± 7.2; 5.2 ± 4.9; 23 ± 4.2), with P<0.001 for 2,3DPG. While 2,3DPG levels could result from diminished oxygen, the abnormalities in enzyme activity are due mainly to the presence of young red blood cells: there was a positive correlation between PK activity and nucleated red blood cells (P<0.001, r=0.61) and a negative correlation between mature erythrocytes and PK activity (P<0.001, r= -0.46). This is confirmed by the derivative curve of phragyligram for groups 4 and 5, showing 2 or 3 peaks corresponding to different erythrocyte populations. (1) Jain N.C. (1993) Essential of Veterinary Hematology