Cultured endothelial cells maintain their L-arginine level despite the continuous release of EDRF

Endothelial cells cultured from bovine aorta and grown on microcarrier beads contain 107 +/- 9 microM L-arginine (Arg; n = 11). When packed into a jacketed chromatography column and perfused with Krebs solution, the cells showed a substantial and sustained release of endothelium-derived relaxing factor (EDRF) for up to 2 h, which was further enhanced by infusions of adenosine diphosphate (4 microM). In contrast to other amino acids, such as L-alanine, L-aspartate, L-glutamine, L-glutamate or L-serine, which showed a time-dependent decrease to less than 30% of their original level within 2 h, Arg remained at control levels for 30 min and decreased only by 25% after 2 h. Thus endothelial cells can generate Arg from an intracellular source to maintain their Arg level despite the continuous formation of EDRF.