Inhibition of Phosphorylation During Electrical Excitation of Frog Nerves

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Abstract
Phosphorylation was studied in isolated frog sciatic nerves during excitation, using radioactive P32 as a tracer. The various phosphorylated intermediates were separated by means of the anion exchange resin, Dowex-1. Stimulation for a period of 30 minutes resulted in an increase of almost all P-intermediates studied, with the exception of phosphocreatine (PCr). DPN showed the greatest increase (58%). With the exception of orthophosphate (P) the radioactive specific activity of all fractions decreased; PCr, G-6-P and ATP decreasing over 15% and DPN 34%. The activity of P increased 20% over the control. The relative specific activity of all fractions from stimulated nerves decreased, over 25% in the case of PCr, ATP and G-6-P, and 30% in the case of DPN. Specific activity-time relations were studied, and here, too, there was a clear indication that phosphorylation was inhibited during excitation of frog nerves. Insofar as oxidative and glycolytic metabolism increase phosphorylation and oxidation during excitation, it is believed that an actual ‘uncoupling’ occurs during activity in nervous tissue. Results are discussed in relation to alternative pathways of energy transfer and noncarbohydrate sources of energy.

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