Metabolism of phospholipides associated with cell division

Abstract

Male Holtzman rats 6–7 months old were partially hepatectomized and sacrificed 18 hr. or 3 days later. Five hours prior to sacrifice, acriflavine at a level of 2 mg./100 g. body weight was administered subcutaneously to the experimental (treated) animals, and 1 hr. prior to sacrifice both the treated and untreated rats received a subcutaneous injection containing 0.45 μc. P 32/g. body weight. The uptake of P 32 and total P in the acid-soluble, lecithin, cephalin, sphingomyelin, and DNA fractions, and the amounts of di-, tri-, tetra-, and pentaenoic acids were measured in the livers of all animals. The uptake of P 32 in livers of unoperated control animals was much more rapid in the cephalin than in either the lecithin or sphingomyelin fractions. During “regeneration” following partial hepatectomy, the P 32 uptake in the lecithin fraction increased markedly, reaching a maximum at 3 days when mitotic activity was highest. During this period, uptake in the sphingomyelin was increased to a smaller extent, while that in the cephalin fraction was not elevated prior to the onset of mitosis (18 hr.), but was elevated slightly and nonsignificantly at 3 days. Acriflavine, a preprophase inhibitor, caused a marked inhibition of P 32 uptake in all of the phospholipides and in DNA in the animals 18 hr. following partial hepatectomy; 3 days afterward it markedly inhibited mitosis but had little or no effect on the incorporation of P 32 into the phospholipides. This suggests that the increased phosphorylation of lecithin shown to be associated with mitosis occurs during preprophase processes. The data do not bear out a relationship between unsaturated fatty acid concentrations and mitosis.