Age-related changes and inheritance of lactate transport activity in red blood cells.

The research examines the changes in lactate transport activity in horse red blood cells with age and the heritability of this attribute. It observed that this activity, performed by the H+-monocarboxylate co-transporter (MCT), is highest in young horses, declines until about 2-3 years of age, and then tends to rise again.

MCT Activity in Red Blood Cells

• The study records lactate transport activity in red blood cells of horses ranging from 2 weeks to 8 years old. This is carried out by H+-monocarboxylate co-transporter (MCT), which is the main lactate carrier in these cells.
• The study found that there are considerable differences in the level of MCT activity among different horses.

Changes in MCT Activity With Age

• The research notes that the level of MCT activity is highly age-dependent. The activity is at its highest in foals, then declines to reach a low point when the horse is about 2 to 3 years old. After this nadir, the level of activity starts to rise again.
• The findings suggest that the age of the horse has a significant impact on the performance of MCT.

Interindividual Variation and Grouping

• The study also identified two distinct groups of horses based on their MCT activity. Those with low activity are categorized as Low Transporters (or LT group), and those with high activity as High Transporters (or HT group).
• An important observation concerning these groups is that a horse does not typically switch from one group to the other. That is, an LT horse does not become an HT horse and vice versa.

Heritability of MCT Activity

• The researchers also analyzed MCT activity from four sires, fifteen dams, and their fifty-two offspring. The data indicated that MCT activity is a heritable trait.
• Additionally, it was shown that low MCT activity could be the result of a recessive allele located in a single autosomal locus – a position on a chromosome where the gene responsible for the trait is located.
• Given the significance of MCT activity to the lactate concentration in red blood cells, this finding may have various physiological implications.