[Dynamics of orotic acid metabolism in chick tissues].

The processes of pyrimidine nucleotides metabolism were analyzed in cells of chicken small intestine mucosa using the kinetic series-parallel model of the first order equations. The rate constants are calculated for absorption of [2-14C]orotic acid by mucosa cells, its accumulation in blood anc conversion to uridine nucleotides. Stages of uridine nucleotides conversion to cytidine ones and their incorporation into RNA are not described by the system of the first order equations based on the series-parallel model with the single-channel utilization of orotic acid through the pyrimidine pathway. The model into two pathways of free nucleotides metabolism and two individual flows of precursors into RNA corresponds qualitatively to the obtained experimental data. Metabolism of orotic acid along two separate channels might be typical of the chicken liver.