Immunohistochemical analysis of MCT1 and CD147 in equine skeletal muscle fibres.

This research explores the expression of Monocarboxylate transporter 1 (MCT1) and its ancillary protein CD147 in different types of horse muscle fibres. The findings indicate that MCT1’s expression corresponds to the oxidative capacity of muscle fibres, but CD147’s expression does not vary among fibre types.

Understanding MCT1 and CD147

• Monocarboxylate transporter 1 (MCT1) and its ancillary protein CD147 are significant as they help in the efflux (flow out) of lactate from the muscle. Lactate is a product of anaerobic metabolism – energy production without oxygen – and can contribute to muscle fatigue.
• MCT1 primarily acts as a lactate transporter, and CD147 is essential for the functioning of MCT1 by supporting its proper placement and stability in the cell membrane.

The Research Approach

• Researchers used immunohistochemistry, a technique widely used in pathology to visualize the presence and location of proteins in tissue sections, to study the expression of MCT1 and CD147 in different equine skeletal muscle fibres (type I, IIA, IIAB, IIB) of horse gluteal muscle.
• The study considered staining intensity as an indicator of the presence of these proteins. The intensity in different parts of the muscle fibres (cytoplasm and membranes) and the capillaries was noted.

Major Findings

• The study found that the staining intensity of MCT1 in the cytoplasm and in the membranes of the different fibre types decreased following a pattern of I=IIA>IIAB>IIB. This decrease in the staining intensity denotes a decrease in the presence of MCT1, indicating lower lactate transport capacity.
• This observed decrease in MCT1 staining intensity correlated with the oxidative capacity of the muscle fibres, with type I and IIA having higher and type IIB having the lowest oxidative capacities.
• In contrast, CD147 showed even staining across all fibre types in the plasma membranes (outer coverings), thus indicating its universal presence irrespective of fibre type. However, the staining in the cytoplasm followed a similar pattern as that of MCT1.

Implications of the Research

• The findings from this study reveal how the expression of MCT1 follows the oxidative capacity of muscle fibres, but the expression of CD147 does not differ among fibre types. Hence, it implies that the lactate transport capacity is primarily dependent on the oxidative capacity of muscle fibres.
• Identifying specific antibodies for MCT1 and CD147 in horses could help future studies assess lactate efflux from different muscle fibre types more effectively. Such studies can offer insights into muscle fatigue and performance in horses, contributing to improved training and conditioning regimes.