PURINE AND PYRIMIDINE NUCLEOTIDE-METABOLISM OF VASCULAR SMOOTH-MUSCLECELLS IN CULTURE

1. Cultures of vascular smooth muscle cells accumulate extracellular b reakdown products of purine and pyrimidine nucleotides that, over 9 hr , represent 60+/-7 and 78+/-17%, respectively, of the intracellular nu cleotide content. 2. The accumulation is stimulated during contracture with 20 mM KCl or 70 mu M carbachol, consistent with the notion that both pyrimidine and purine nucleotides are involved in the energetics of smooth muscle contracture. 3. Because the intracellular levels of p yrimidine and purine nucleotides remain constant, it appears likely th at rates of synthesis match the rates of release. 4. Ectonucleotidases are present that can degrade ATP, UTP, and CTP. High-energy nucleotid es may be the primary products released.