Variants of the Solute Carrier SLC16A1 Gene (MCT1) Associated With Metabolic Responses During a Long-Graded Test in Road Cyclists.

ABSTRACT

Variants of the solute carrier SLC16A1 gene have been associated with alterations in MCT1 expression, because of a lactate (La) transport deficiency across the cell membrane and a blood La accumulation. The aim of this study was to associate the allelic and genotypic frequencies of 1470T>A, 2917(1414) C>T, and IVS3-17A>C variants relative to the blood La kinetics and metabolic responses to a progressive effort until exhaustion. Twenty-five well-trained road cyclists performed a long-graded laboratory test 10 minutes at 2.0 W·kg, first step at 2.5 W·kg with increments of 0.5 W·kg every 10 minutes until exhaustion. Blood La, nonesterified fatty acids (NEFAS), and glucose levels were measured; fat and carbohydrate oxidation rates were estimated through stoichiometric equations. Three variants of SLC16A1 gene were determined for each subject, which were divided in two groups wt (wild type)/mt (mutated type) and mt/mt genotype group versus wt/wt genotype group. Metabolic responses were compared between both groups with an unpaired Student's t-test; Friedman and Wilcoxon tests were performed for nonparametric data. The statistical significance was set at p ≤ 0.05. For 1470TA polymorphism, no significant blood La differences were found between groups. 2197(1414)C>T allele carriers and IVS3-17A>C carriers showed significantly higher blood La levels, lower blood NEFAS, and glucose levels at submaximal intensities. These findings open a new perspective to investigate SLC16A1 variants (1470TA and IVS3-17A>C) on La deficiency transport and its regulation/interaction with other metabolic pathways. Future studies would be needed to clarify whether 1470T>A, 2917(1414)C>T, and IVS3-17A>C allelic/genotypic distribution benefit performance in endurance athletes.