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

This research study investigates the difference in energy metabolism between racehorses and riding horses by measuring the specific enzymes responsible for ATP production in glucose metabolism. The findings suggest that racehorses have significantly higher enzyme activity indicating elevated energy metabolism, and the research proposes a potential parameter to evaluate these differences.

Research Objective and Methodology

• This study aims to explore the change in metabolic states of race horses with training by measuring the activity of key enzymes involved in the production of ATP, a crucial energy molecule, as part of glucose metabolism.
• The research focuses on the enzyme malate dehydrogenase (MDH), a vital component of the NADH shuttle – also known as the malate-aspartate shuttle.
• The measurements were carried out in peripheral leukocytes of horses, a type of white blood cell. Blood was drawn from both race horses and riding horses (used as a comparison group) to examine any differences in enzyme activity.
• Cytosolic and mitochondrial MDH activities were measured, as well as the ratio of MDH to another enzyme, lactate dehydrogenase (LDH), referred to as the M/L ratio.
• Further confirmation of MDH activity levels was obtained using RT-PCR analysis on total RNA extracted from the blood samples.

Key Findings

• The study found no significant differences in plasma glucose and insulin concentrations between race horses and riding horses, indicating that these factors are not responsible for any observed differences in energy metabolism.
• The research revealed higher levels of cytosolic and mitochondrial MDH activity in the leukocytes of race horses compared to riding horses, suggesting heightened energy metabolism in race horses.
• The M/L ratio in leukocytes was also found to be significantly higher in race horses. The elevation of this ratio is considered to reflect an increase in energy metabolism in animal tissues.
• The researchers propose that the M/L ratio might be used as a useful parameter to evaluate differences in energy metabolism between different types of horses, or potentially between different training states.