Effect of fasting on the metabolism of cytidine nucleotides in the liver of intact and alpha-hexachlorocyclohexane-treated rats.

The utilization of (2-14C)orotic acid for the synthesis of cytidine components of the acid-soluble extract and for the RNA cytosine is decreased in the liver of rats which fasted for 24 or 72 h. The depression of the specific activity of the cytidine components is greater in animals which received alpha-HCH during the 24-hour interval after removal of food than in the control group; by contrast, the specific activity of the cytidine components again increases in rats fasting for 72 h. Analogous changes also occurred in the specific activity of RNA cytosine. Both the (U-14C)cytidine uptake and its utilization for the synthesis of RNA cytosine are enhanced in fasting rats; the administration of alpha-HCH has a potentiating effect. The total content of cytidine components of the acidsoluble extract of 1 g of liver tissue is enhanced 24 h after the animals of the control and experimental group were deprived of food. There are no marked differences in the concentration of the uridine components. Fasting has an additive effect on the increase of cytochrome P-450 level in the alpha-HCH treated rats. Alpha-HCH = alpha-1,2,3,4,5,6-hexachlorocyclohexane.