MEANING OF ENERGETIC PARAMETERS

High energy phosphates (HEP: ATP & phosphocreatine (PCr)) are to be considered under qualitative (free energy of hydrolysis) and quantitative (concentration) aspects. Energy charge is also a (normalized) concentration related parameter. Owing to high turnover rates concentration (HEP stores) provides sufficient energy only for 10 to 20 s in the case of interruption of supply. Utilization (without immediate supply) leads to rapid drop of free energy which - owing to the CK reaction - is indicated by rapid drop of PCr and the respective ratios. Critical reduction of free energy appears to be prevented by various protective mechanisms reflected in phenomena of early hypoxic failure, hibernating and stunning.