Title: Argininosuccinate synthetase mRNA and activity are induced by immunostimulants in vascular smooth muscle. Role in the regeneration or arginine for nitric oxide synthesis
Abstract: Nitric oxide synthase produces NO, citrulline, water, and NADP at the expense of arginine, NADPH, and dioxygen.While citrulline has been considered to be an inert by-product of the high output inducible isoform of NO synthase (iNOS), we show here that immunostimulants induce a metabolic pathway in vascular smooth muscle cells, which enables them to regenerate arginine from citrulline.Regeneration of arginine from citrulline is accomplished by two urea cycle enzymes: argininosuccinate synthetase (AS) and argininosuccinate lyase (AL).Whereas AL is constitutive to vascular smooth