The effect of succinate and amytal on the reduction of acetoacetate in animal tissues

It has recently been shown (Kulka, Krebs & Eggleston, 1961) that succinate promotes the formation of ,-hydroxybutyrate from acetoacetate in sheep-heart homogenates.An explanation was put forward which is based on the fact that succinate is oxidized in preference to substrates requiring a pyridine nucleotide-linked dehydro- genase.As the electrons from succinate and from reduced pyridine nucleotide travel to oxygen by a common pathway at the cytochrome level the preferential availability of the electrons from succinate blocks the transfer of electrons from reduced pyridine nucleotide to oxygen.At the same time the oxidation of succinate provides a substrate, malate, which reduces pyridine nucleo- tide.These two circumstances increase the amounts of reduced pyridine nucleotide available for the reduction of acetoacetate.This paper presents further evidence in support of this concept.' -Hydroxybutyrate' Substance tested found (16,umoles) (,umole) Succinate 0-05 Fumarate 0 L-Malate 0 Citrate 0-25 a-Oxoglutarate 0-16 Pyruvate 0-36 L-Lactate 0-05 Butyrate 0 05 Crotonate 0-14 Glucose 0.09 Amytal (5 ,umoles)