[Pyrimidine nucleotide triphosphate control of the phosphorylation of cytidine in the rat heart].

The phosphorylation of 5 microM cytidine by the isolated perfused rat heart was increased by 50 and 120% respectively, when the myocardial UTP content was increased by 30%, 1 hr. after the treatment of animals with isoprenaline (5 mg/kg; s.c.) and by 50%, 6 hrs. after the treatment of animals with galactosamine (430 mg/kg; i.p.). On the other hand, this rate of synthesis of cytidylic nucleotides from cytidine was not decreased when the intracellular UTP and cytidylic nucleotide levels were increased through 130 and 90% respectively (12 hrs. after isoprenaline treatment).