Effect of Starvation, Dietary Protein and Partial Hepatectomy on Rat Liver Aspartate and Ornithine Carbamoyltransferases

Activity of Aspartate Carbamoyltransferase in Ovine Tissues

“…The abrupt and prolonged (36 days) restriction of food intake of mature sheep resulted in slightly reduced (20-27 %) levels of ACT in liver, ileum and duodenum. Durkin and Nishikawara, (1971) also found a 24 % reduction in the level of ACT in rat liver following a short-term (2-day) starvation period.…”

“…When immature sheep were refed, the level of ACT in the liver, ileum and duodenum increased rapidly, and was 20-97 % higher than in the corresponding control tissues. Durkin and Nishikawara (1971) reported that in rat liver growth was stimulated by high dietary protein without a corresponding change in ACT activity and presumably, therefore, in pyrimidine biosynthesis, while in regenerating hepatic tissue the ACT activity per milligram tissue increased markedly. Hence, compensatory growth in these refed sheep appears to be more akin to the rapid growth following partial hepatectomy than to growth stimulated by change from a low to a high protein diet in which the level of ornithine transcarbamylase and not ACT is reported to increase markedly.…”

“…Whereas DNA synthesis is depressed, RNA production is maintained and responds rapidly to an inducing stimulus (Shaw and Fillios 1968;Siimes and Dallman 1974). The activity of aspartate carbamoyltransferase (ACT; EC 2.1.3.2), which catalyses the first step in the biosynthesis of pyrimidines required for RNA synthesis, was found to be reduced in the liver of rats starved for 2 days but almost doubled in rat liver after partial hepatectomy (Durkin and Nishikawara 1971).…”