Glyoxylate cycle in the rat liver: effect of vitamin D3 treatment

Evidence for the glyoxylate cycle in the mammalian rat liver was sought. Activity of two unique glyoxylate cycle enzymes, isocitrate lyase and malate synthase, was found in rat liver homogenates. Vitamin D3 treatment of rachitic animals produced a five- and fourfold increase, respectively, in the activity of these enzymes. Vitamin D3 also increased the peroxisomal fatty acid oxidation and the accumulation of glycogen in liver slices in the presence of palmitate. These data suggest that the mammalian rat liver can convert fatty acid carbon to carbohydrate carbon directly.