Vitamin E deficiency in the rat: I. Effect of substrate concentration on respiratory decline in liver homogenates from rats fed a vitamin E-deficient diet

Abstract

Male Holtzman rats were maintained for approximately 3 weeks on either a vitamin E-deficient or vitamin E-supplemented diet. The capacity of liver homogenates from these animals to oxidize succinate, α-ketoglutarate, β-hydroxybutyrate, pyruvate, malate, and DPNH was measured over extended periods of time, and in the presence of different substrate concentrations. The decline in rate of oxidation, with time of incubation, differed, depending on the substrate employed, the concentration of substrate, and whether vitamin E was present or absent in the diet of the donor animal. The concentration of α-ketoglutarate, β-hydroxybutyrate, pyruvate, and malate influenced the respiratory decline of vitamin E-deficient homogenates differently from the manner in which it affected the decline of supplemented homogenates. There was no apparent differences in respiratory decline between deficient and supplemented homogenates due to differences in succinate or DPNH concentration at any given substrate concentration studied.