Pharmacodynamics of (A) native rhArg1 and (B) pegylated rhArg1 on plasma arginine in rats. Sprague-Dawley rats were each injected i.p. with native or pegylated rhArg11. Plasma was collected at the indicated times, and arginine in each sample was determined by amino acid analysis. The data given as the means and 1 SD of 8 animals.