Acute and Chronic Resistance Training, Acute Endurance Exercise, nor Physiologically Plausible Lactate In Vitro Affect Skeletal Muscle Lactylation

Abstract

We examined changes in skeletal muscle protein lactylation and acetylation in response to acute resistance exercise, chronic resistance training (RT), and a single endurance cycling bout. Additionally, we performed in vitro experiments to determine if different sodium lactate treatments affect myotube protein lactylation and acetylation. The acute and chronic RT study (12 college-aged participants) consisted of 10 weeks of unilateral leg extensor RT with vastus lateralis (VL) biopsies taken at baseline, 24 h following the first RT bout, and the morning of the last day of the RT bout. For the acute cycling study (9 college-aged participants), VL biopsies were obtained before, 2 h after, and 8 h after 60 min of cycling. For in vitro experiments, C2C12 myotubes were treated with varying levels of sodium lactate, including LOW (1 mM for 24 h), HIGH (10 mM for 24 h), and PULSE (10 mM for 30 min followed by 1 mM for 23.5-h). Neither acute nor chronic RT significantly affected nuclear or cytoplasmic protein lactylation. However, cytoplasmic protein acetylation was significantly reduced following one RT bout (-15%, p = 0.002) and chronic RT (-16%, p = 0.006). Cycling did not acutely alter post-exercise global protein lactylation or acetylation patterns. Lastly, varying 24 h lactate treatments did not alter nuclear or cytoplasmic protein lactylation or acetylation, cytoplasmic protein synthesis levels, or myotube diameters. These findings continue to support the idea that exercise induces more dynamic changes in skeletal muscle protein acetylation, but not lactylation. However, further human research with more sampling timepoints and a lactylomics approach are needed to determine if, at all, different exercise modalities affect skeletal muscle protein lactylation.

Keywords: hypertrophy; protein acetylation; protein lactylation; skeletal muscle.

Figure 1

Study schematic. This graphic gives a visual overview of the acute and chronic resistance training study, the acute cycling study, and cell culture model (constructed using Biorender.com, accessed on 14 August 2024).

Figure 2

Effects of acute and chronic resistance training on nuclear and cytoplasmic protein lactylation and acetylation. Biopsies were obtained prior to the intervention (pre), 24 h following the first exercise bout (24 h post-bout 1), and following the 10-week intervention (post-10 weeks) in 12 participants. No significant alterations occurred with cytoplasmic protein lactylation (a), nuclear protein lactylation (b), nuclear protein acetylation (d), or nuclear H3K9 acetylation (e). However, cytoplasmic protein acetylation (c) was significantly reduced with one bout of resistance exercise and chronic training. Representative Western blots for the protein targets (f) are presented. Bar graphs are mean and standard deviation values, with individual respondent data overlaid.

Figure 3

Acute and chronic resistance effects on the expression of select nuclear and cytoplasmic proteins associated with acetylation and lactylation. Biopsies were obtained prior to the intervention (pre), 24 h following the first exercise bout (24 h post-bout 1) and following the 10-week intervention (post-10 weeks) in 12 participants. No significant alterations occurred with cytoplasmic or nuclear HDAC2 protein expression (a,b). Cytoplasmic and nuclear HDAC6 protein levels were significantly reduced with one bout of resistance exercise (c,d). No significant alterations occurred with cytoplasmic or nuclear LDHA protein expression (f,g). Representative Western blots for the protein targets (e,h) are presented. Bar graphs are mean and standard deviation values with individual respondent data overlaid.

Figure 4

Acute cycling bout data. Global protein lactylation (a) and global protein acetylation (b) markers assessed at baseline, 2 h post-, and 8 h post-60 min cycling bout. Representative Western blots for the protein targets (c) are presented. Bar graphs are mean and standard deviation values, with individual respondent data overlaid.

Figure 5

C2C12 sodium lactate treatment data. Cytoplasmic (a) and nuclear (b) protein lactylation levels were not different between treatments. Cytoplasmic (c) and nuclear (d) protein acetylation levels were also not different between treatments. Finally, myotube diameters (f) and cytoplasmic MPS levels (g) were not significantly different between treatments. Representative Western blots for the protein targets (e) are presented, and representative myotube images are also presented (h); note inset white bars are 100 µm. Bar graphs are mean and standard deviation values with individual replicate values overlaid.