Skeletal muscle inosine monophosphate formation preserves ΔGATP during incremental step contractions in vivo

• DOI: 10.1152/ajpregu.00192.2024
• Publication Date: 2024-12-20T22:30:52Z
• Authors: Zoe H. Smith; Christopher M. T....; Kate L. Hayes; Jane A. Kent
• Keywords: Inosine monophosphate; Inosine; Adenosine triphosphate

The cause and consequences of inosine monophosphate (IMP) formation when ATP declines during muscular contractions in vivo are not fully understood. purpose this study was to examine the role IMP maintenance Gibbs free energy for hydrolysis (∆G ) dynamic increasing workload, implications loss vivo. Eight males (27.5, 25-35yr, median, range) completed an 8-minute incremental protocol (2-minute stages isotonic knee extensions (0.5Hz)) a 3-Tesla magnetic resonance (MR) system. Phosphorus MR spectra were obtained from extensor muscles at rest recovery. Although demand met primarily by oxidative phosphorylation, [ATP] decreased 8.2 mM 7.5 (range 6.4-8.0) [IMP] increased 0 0.6 (0.1-1.7) mM. Modeling showed that, absence formation, excess ADP would result less favorable ∆G (p<0.001). Neither nor had returned baseline following 10 minutes recovery Notably, ∆[ATP] linearly related post-contraction reduction muscle capacity (r=0.74, p=0.037). Our results highlight importance preserving cellular status avoiding increases above that necessary stimulate production pathways. However, consequence incomplete [ATP], which turn contractions. These likely have generate adequate repeated bouts work.