Hypoxanthine

Hypoxanthine is an intermediate purine catabolite produced from AMP dephosphorylation via IMP during high-intensity exercise when ATP resynthesis cannot keep pace with demand, reflecting the degree of adenine nucleotide degradation in skeletal muscle. Salivary hypoxanthine rises sharply with anaerobic exercise intensity and serves as a sensitive marker of energy depletion and purine nucleotide catabolism. Sahlin et al. (1991) established the relationship between muscle IMP accumulation and hypoxanthine release, forming the basis for its use as a muscular load and oxidative stress marker.