The effect of fumarate and of p-nitrophenol on the synthesis of fatty acids in homogenates of the mammary gland

The effect of glucose and acetate on milk secretion by the perfused goat udder

“…This belief is strengthened by the failure of fumarate in the absence of glucose to have any effect on milk secretion or 02 uptake (cf. Terner, 1956). Therefore it seems that the energy for secretion comes from some pathway of glucose metabolism other than the Krebs cycle and one which is not available to acetate.…”

“…Acetate plu8 fumarate Terner (1956) has shown that fumarate stimulates fatty acid synthesis by mammary-gland slices in the presence of acetate. We therefore tested acetate plus fumarate as substrates on the gland (Fig.…”

Pyruvate and Glucose as Precursors of Acetoacetate

“…The ability of glucose to regenerate reduced pyridine nucleotide in an aerobic system, may explain not only its non-ketogenicity, but also its effectiveness in stimulating the synthesis of fatty acids from acetate, originally demonstrated in mammary slices (9) and later ob-served in actively respiring mammary homogenates metabolizing acetate in the presence of fumarate ( 8).…”

“…Homogenates of mammary glands of lactating guinea pigs, prepared as described in a previous study of lipogenesis (8), and rabbit kidney cortex homogenates were incubated in a reaction mixture containing in addition to KCl: MgC12, 0.01 M; nicotinamide, 0.02 M; DPN, 3 x l P M ; ATP, 0.001 M ; phosphate buffer, pH 7.4, 0.01 M aminotrishydroxymethylmethane (tris) buffer pH 7.4, 0.01 M and carrier acetoacetate, 0.01 M. After incubation with C14-labeled substrates (0.005-0.01 M ) in the Warburg apparatus, the reaction mixtures were acidified and the bound C02 collected in the NaOH in the center wells which had served to absorb the COa during the measurements of O2 consumption. The contents of the center wells were then removed, replaced by fresh NaOH and the acetoacetate was decarboxylated by the addition of aniline citrate.…”