Post-exercise cold-water immersion increases Na+,K+-ATPase α2-isoform mRNA content in parallel with elevated Sp1 expression in human skeletal muscle

We investigated the effect of a session of sprint-interval exercise on the mRNA content of NKA isoforms (α 1-3 , β 1-3 ) and FXYD1 in human skeletal muscle. To explore some of the cellular stressors involved in this regulation, we evaluated the association between these mRNA responses and those of the transcription factors Sp1, Sp3 and HIF-1α. Given cold exposure perturbs muscle redox homeostasis, which may be one mechanism important for increases in NKA-isoform mRNA, we also explored the effect of post-exercise cold-water immersion (CWI) on the mRNA responses. Muscle was sampled from nineteen men before (Pre) and after (+0h, +3h) exercise plus passive rest (CON, n=10) or CWI (10°C; COLD, n=9). In COLD, exercise increased NKAα 2 and Sp1 mRNA (+0h, p0.05). In both conditions, exercise increased NKAα 1 , NKAβ 3 and HIF-1α mRNA (+3h; p <0.05), decreased NKAβ 2 mRNA (+3h; p0.05). These human findings highlight 1) sprint-interval exercise increases the mRNA content of NKA α 1 and β 3 , and decreases that of NKA β 2 , which may relate, in part, to exercise-induced muscle hypoxia, and 2) post-exercise CWI augments NKAα 2 mRNA, which may be associated with promoted Sp1 activation.