The metabolism of
pyrimidine nucleotides in the myocardium is poorly understood. The turnover of these
nucleotides is high, whereas their concentration is rather low. The de novo pathway of synthesis does not seem very efficient, although the utilization of
nucleosides could represent the major pathway for
pyrimidine nucleotide synthesis. In rat blood,
cytidine could be the major precursor for
pyrimidine nucleotide synthesis. The precursor, whatever its exact nature (
uridine or
cytidine), could be species dependent, and the liver could a major role in providing blood
nucleosides. Owing to the essential role of
pyrimidine nucleotides in the synthesis of macromolecules, acute or chronic alteration of the metabolism of these
nucleotides could have crucial consequences on heart viability and function. Providing
pyrimidine precursors to the heart, isolated or in situ, induces functional and metabolic effects on the heart. The experimental results suggest that such interventions could be beneficial in clinical situations such as
cardioplegia, heart preservation, or recovery from
ischemia.