Metabolic Acidosis Reduces Exercise-induced Up-regulation Of PGC-1alpha mRNA

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May 28 4:15 PM - 4:30 PM

PURPOSE: Recent research has shown that sodium bicarbonate (NaHCO₃) supplementation during interval training results in greater improvements in mitochondrial respiration and endurance performance. It was hypothesised that this may have been due to a negative effect of metabolic acidosis on the up-regulation of genes responsible for aerobic adaptations. A key regulator of mitochondrial biogenesis is peroxisome proliferator activated receptor gamma co-activator (PGC-1)alpha. The purpose of this study was to determine the effects of metabolically-induced acidosis on the exercise-mediated mRNA response of PGC-1alpha mRNA expression.

METHODS: Eight active males (Mean±SD, age, 25 +/− 6 y, body mass 83.7 +/− 9.0 kg, VO_2max 47.6 +/− 7.6 mL/kg/min) performed 10x2 min cycle intervals at 80% VO_2max intensity on two separate occasions (separated by ~2 weeks). Participants ingested either ammonium chloride (ACIDOSIS) or calcium carbonate (PLACEBO) the day before and on the day of the exercise trial in a randomized, counterbalanced order, using a crossover design. Biopsies were taken from the vastus lateralis muscle before, immediately after exercise, and also after 2 and 6 h of recovery. The RNA content of PGC-1alpha was determined by RT-PCR and normalized to total cDNA content determined by OliGreen.

RESULTS: Exercise markedly increased PGC-1alpha mRNA content at 2 and 6 h of recovery in both conditions. However, ACIDOSIS was associated with a suppressed response relative to the PLACEBO condition at 2 and 6 h of recovery (~2-3 fold decrease, respectively; P<0.05). A similar response was also observed for citrate synthase mRNA at 2 h of recovery.

CONCLUSION: The present data demonstrate that metabolic acidosis reduces exercise-induced up-regulation of PGC-1alpha mRNA suggesting that metabolic acidosis may interfere with training-induced mitochondrial biogenesis.