... exchange resin (Na+form), and eluted with 1.2 mL of water. l-[3H]Citrulline was quantified by liquid scintillation spectroscopy. The retentionof l-[3H]arginine by the column was greater than 98%.Enzyme ... determination of ATP production, hearts wereexcised, washed with saline, treated with proteinase K(1 mgÆmL)1) for 30 s, washed with buffer A (220 mmmannitol, 70 mm sucrose, 1 mm EGTA, 20 ... was measured in the resultant supernatants by HPLC with a 4 · 250 mm ProPac PA1 column (Dionex,Barcelona, Spain) [70]. After stabilization of the column with the mobile phase, samples (20 lL) were...