Lactate Transport in Red Blood Cells by Monocarboxylate Transporter MCT1 and Its Accessory Protein CD147 In Brazilian Sport Horses of Different Performance Levels

Abstract

IntroductionThe Brazilian sport horse (BH) was specifically developed for jumping competition. Monocarboxylate transporters are key regulators of cell pH and therefore facilitate co‐transport of protons and lactate. Lactate transport in red blood cells (RBCs) is bimodal (high [HT] and low transport [LT]) and is related to CD147 levels. This study aimed to quantify MCT1 and CD147 protein levels in BH after an incremental jumping test (IJT).MethodsSixteen horses were distributed into two groups: low‐level jumpers (LL, n = 8), able to jump up to 1.00 m, and high‐level jumpers (HL, n = 8), able to jump up to 1.20 m. The IJT consisted of three steps, each with forty jumps at increasing heights (0.40, 0.60, and 0.80 m). Blood samples were collected before and after the IJT. The YSI 2300 method was used to determine plasma lactate concentration [Lac]p. RBC membranes were purified, and MCT1 and CD147 levels were measured by Western blotting. A Student's t‐test and Pearson's correlation (P<0.05) were employed.ResultsThe HL group displayed lower [Lac]p, indicating prevalence of the aerobic pathway in this group. The results showed no difference in the expression of the transporters between times or groups and a positive correlation (r = 0.67, P<0.0001) between MCT1 and CD147. In both groups [Lac]p didn't correlate with the amount of MCT1 or CD147. Most of the horses appeared to have high lactate transport activity. The CD147/MCT1 ratios for LL and HL were equal.ConclusionsBH showed no difference in MCT1 and CD147 expression between conditioning levels.Ethical Animal ResearchAll procedures were approved by the institutional animal care and use committee of the university (CEUA, Process: 019281/13). Explicit owner informed consent for participation in this study is not stated. Sources of funding: FAPESP ‐ Fundação de Amparo à Pesquisa do Estado de São Paulo (Process 2011/11080‐0). Competing interests: none.