ENERGETICS OF RESTING ANAEROBIC FROG GASTROCNEMIUS AT DIFFERENT TEMPERATURES BY P-31-NMR

The net rate of phosphocreatine hydrolysis {A figure is presented}, and tissue pH were determined in anaerobic resting frog (Rana Ridibunda Ridibunda) gastrocnemii by 31P-NMR in the temperature (T) range from 5 to 30°C. Absolute {A figure is presented} values from 0.36 to 10.07 mM/h were estimated assuming a resting [PCr] of 26 mM at 20°C. The corresponding Q10 values ranged from 2.1 (30°C) to 17.5 (5°C). Muscle pH was found to be T-dependent with a 10°C drop in T resulting in an increase of 0.1 pH units. At any given T, pH was found to be constant over a period of at least one hour (30°C) from the onset of anaerobiosis. Based on simultaneous {A figure is presented} and pH estimates, the contribution of anaerobic glycolysis {A figure is presented} to the overall rate of ATP resynthesis {A figure is presented} was estimated assuming a ∼P/La ratio of 1.2 {A figure is presented} was then calculated for each investigated T value as the sum of {A figure is presented} and {A figure is presented}. {A figure is presented} was found to vary between 5 and 30°C from 0.79 mM/h to 22.15 mM/h. The present study, besides proposing a methodology for the assessment of high energy phosphates hydrolysis by 31P-NMR spectroscopy at changing T, provides a comprehensive analysis of the T-dependence of anaerobic metabolism of the resting anaerobic frog gastrocnemius, which may be extrapolated to other tissues. © 1990.