Increased myocardial pyrimidine nucleotide synthesis in isoproterenol-induced cardiac hypertrophy in rats

In a first phase (up to 12^h) after the first injection of isoproterenol (5mg.kg^?1 b.w.) the pyrimidine nucleotide pools were increased and the rates of incorporation of inorganic phosphate into the α-phosphate groups of nucleotides were raised from 16 to 58 nmol.g^?1.h^?1 for uracil nucleotides and from 11 to 32 nmol.g^?1.h^?1 for cytosine nucleotides. At a later stage, while the pool sizes decreased slowly toward control levels, these rates of labelling also decreased though still remaining above control values. A similar pattern of changes was induced by the eighth daily isoproterenol injection, but the alterations were attenuated.