Enzyme activities in some types of peripheral leukocytes of thoroughbred race horses before and after the races.

This research focuses on the changes in enzyme activities relating to energy metabolism in the peripheral leukocytes (a type of white blood cell) of thoroughbred race horses, following participation in a race. The study found that there was a significant decrease in certain enzyme activities after racing, although no significant changes were noted in glucose, free fatty acid, triglyceride, and immunoreactive insulin concentrations in the plasma of these horses.

Measurement of Plasma Concentrations and Enzymes Activities

• The researchers measured the plasma concentrations of glucose, free fatty acid (FFA), triglycerides (TG), and immunoreactive insulin (IRI) in the blood of the race horses. These elements are key indicators of the horse’s energy levels and overall metabolic health.
• The activities of specific enzymes associated with energy metabolism were also measured. These included cytosolic hexokinase, malate dehydrogenase (MDH), mitochondrial MDH, and aspartate aminotransferase. These enzymes play important roles in breaking down sugars and other compounds to generate energy in cells.

Post-Racing Changes in Enzyme Activities

• After the races, there was a significant decrease in the activities of some enzymes in the leukocytes of the thoroughbred horses, including cytosolic hexokinase, malate dehydrogenase (MDH), mitochondrial MDH, and aspartate aminotransferase. This suggests that the intense exercise of racing might impact energy metabolising enzyme activities in the horse’s white blood cells.

Cytosolic Ratio of MDH/LDH Activity

• The study also analysed the ratio of MDH to lactate dehydrogenase (LDH) activity in the horse’s leukocytes, referred to as the ML ratio. This ratio decreased significantly post-racing, suggesting it could serve as a potential indicator of energy metabolism changes in race horses.
• More broadly, the researchers propose that monitoring changes in the ML ratio could be a useful technique in evaluating the metabolism and energy management of race horses, potentially improving their performance and health management.