“…Most studies [ 9 , 14 , 18 , 22 , 37 , 40 , 54 , 55 , 56 ] of the acute effects of arginine on endothelial production of nitric oxide in vivo or in vitro have used topical concentrations more than ten times the plasma concentration of 50–75 μ M [ 32 , 33 , 42 , 53 , 57 , 58 ]. Part of the rationale for using high concentrations of arginine for testing is that the intracellular L‐arginine concentration range is 100 μ M to 800 μ M [ 2 , 3 , 28 , 34 ] and even higher in freshly isolated endothelial cells [ 34 ].…”