RESUMEN
Pyruvate dehydrogenase complex (PDC) from rat kidney or pig heart previously inactivated by phosphorylation (PDHP) was activated in vitro by PDHP phosphatase from kidneys of starved or fed rats. Starvation for 48h of the rats from which the PDC was prepared led to a decrease in the rate of activation of PDC at early time periods (< 2min), particularly at submaximal concentrations of Mg 2+. Using intact permeable kidney mitochondria incubated for 15 sec, it was found that starvation of rats more than doubled the Mg 2+ concentration at which the half maximal increment of PDC activity (PDC) was observed. Reduction of PDHP phosphatase activity due to starvation was also apparent when phosphatase was separated from PDC and recombined with PDC from the same or different animals (AU)