Proceedings of The Physiological Society

King's College London (2009) Proc Physiol Soc 14, PC44

Poster Communications

Sodium bicarbonate increases glucose uptake and mitochondrial biogenesis in C2C12 myotubes potentially via the transcriptional co-activator PGC-1α

J. Perez-Schindler1, A. Philp1, K. Baar1

1. Division of Molecular Physiology, University of Dundee, Dundee, United Kingdom.

Ingestion of Sodium Bicarbonate (NaHCO3) during short-term interval training has beneficial effects on cellular metabolism and metabolite transport in both rodents (Thomas et al, 2007) and humans (Edge et al (2006). However, the cellular mechanism for this additive effect remains unclear. The aim of this study was to examine the effect of NaHCO3 administration in C2C12 myotubes. Five days following differentiation, C2C12 myotubes were treated for 72h with either NaHCO3 (5-50mM) or sodium chloride (50mM) as an osmotic control. Following treatment, cells were collected in lysis buffer (50mM Tris pH 7.5; 250mM Sucrose; 1mM EDTA; 1mM EGTA; 1% Triton X-100; 1mM NaVO4; 50mM NaF; 0.10% DTT; 0.50% PIC), centrifuged for 5 mins at 8,000 RPM and the supernatant removed for protein determination. Protein content was determined via western blotting using commercially available antibodies. Total RNA was isolated from 35mm plates using phenol/chloroform. Real time quantitative PCR was performed to measure relative mRNA expression using an Eppendorf Light Cycler PCR machine, SYBR green PCR plus reagents (Sigma Aldrich, Dorset, UK) and custom designed primers. Ten µl PCR reactions were assayed in triplicate on a 96 well heat sealed PCR plate (Thermo Scientific, Leicestershire, UK). Each reaction contained 5µl SYBR green taq, 1µl of forward and reverse primers and 3ul of cDNA (1:2 dilution). Differences between groups were assessed by students paired t-tests (SPSS version 10) whilst all results are expressed as Mean ± SEM. NaHCO3 treatment increased the expression of PGC-1α (302%), GLUT4 (266%) and cytochrome-c (291%) whilst increasing the protein content of GLUT4 (37%), MCT1 and the respiratory chain subunits COX-2 (63%) and COX-4 (42%). Both basal and insulin stimulated glucose uptake were increased following NaHCO3 treatment (68% and 73% respectively) as was basal cell oxygen consumption (10%). Finally NaHCO3 increased the abundance of membrane bound GLUT4 (68%) and MCT1 (73%). Taken together, these findings suggest that NaHCO3 induced chronic alkalosis promotes up-regulation of PGC-1α and its downstream targets COX-2, COX-4, Cytochrome-c and MCT1. Further, NaHCO3 also increases basal and insulin stimulated glucose uptake via increased GLUT4 expression, content and membrane localisation. Further research should assess whether PGC-1α is the specific target for NaHCO3 mediated adaptation and how chronic alkalosis effects PGC-1α signalling.

Where applicable, experiments conform with Society ethical requirements