“…Free FA was measured using NEFA-HR (2) (Wako, Sopachem BV, Ochten, the Netherlands), total cholesterol (Diagnostics Chemicals, Oxford, CT, USA) and triglycerides (Roche Diagnostics Corporation, Indianapolis, IN, USA) by enzymatic colorimetry. F2-isoprostanes were assayed in plasma using negative ion gas chromatography mass spectroscopy as previously described (30). Sildenafil levels were assessed by liquid chromatography-tandem mass spectrometry on silica column with aqueous-organic mobile phase as previously reported (31).…”