Glycolytic Enzyme Activities in Leukocytes of Thoroughbreds Undergoing Training Exercise

Changes in activities of enzymes related to energy metabolism in canine lymphoma cells

Alterations in the activities of enzymes related to energy metabolism in canine lymphoma cells were investigated. Cytosolic pyruvate kinase (PK) and mitochondrial malate dehydrogenase (MDH) activities in lymphoma cells were significantly higher than those in lymphocytes obtained from lymph nodes of healthy dogs, whereas cytosolic lactate dehydrogenase (LDH) activity was significantly lower in lymphoma cells. The cytosolic M/L ratio (MDH activity/LDH activity), which is considered to be a good indicator of energy metabolism related to glucose utilization in animal tissues, was significantly higher in lymphoma cells than in the normal lymphocytes.

Cytosolic ratio of malate dehyrogenase/lactate dehydrogenase activity in peripheral leukocytes of race horses with training

The activities of the enzymes involved in the malate-aspartate shuttle and m RNA expression of malate dehydrogenase (MDH), a crucial enzyme for the NADH shuttle that produces ATP in glucose metabolism in the peripheral leukocytes of horses, were measured to investigate the change in metabolic states with training. There were no significant differences in plasma glucose and immunoreactive insulin concentrations between race horses and riding horses, used as a comparable reference. The cytosolic and mitochondrial MDH activities in leukocytes of race horses were significantly higher than those of riding horses. High activities of MDH in leukocytes of race horses were confirmed by RT - PCR analysis on the total RNA extracted from the whole blood. The cytosolic ratio of MDH /lactate dehydrogenase (LDH) activity (M/L ratio) in leukocytes of race horses was significantly higher than in those of riding horses. Increase in the M/L ratio was considered to reflect elevation of energy metabolism in animal tissues. The M/L ratio may be a useful parameter to evaluate the difference in metabolic states between race horses and riding horses.