Fig. 4.

(A) Pharmacokinetics of [¹⁵N]nitrate (Na¹⁵NO₃, 99 atom% ¹⁵N; Sigma, Germany) at the dose of 101 µmol [¹⁵N]nitrate/kg bodyweight, or [¹⁵N]nitrite (Na¹⁵NO₂, 99 atom% ¹⁵N; Aldrich, Germany) at the dose of 48.4 mmol [¹⁵N]nitrite/kg bodyweight in two male rabbits. (B) Pharmacokinetics of S-[¹⁵N]nitroso-N-acetylcysteine ethyl ester (S¹⁵NACET) in four male rabbits at the doses of 63, 68, 72 and 126 µmol S¹⁵NACET/kg bodyweight. The weight of the rabbits ranged between 1.8–4.8 kg. All substances were administered together with D(+)-glucose (220 mg) in 2 mL of drinking water via a stomach probe. Administered S¹⁵NACET was free of [¹⁵N]nitrite and [¹⁵N]nitrate. Rabbits were treated once only. The first blood sample was taken immediately before drug administration. Horizontal lines at the value of 1.0 indicate the theoretical baseline molar ratio in rabbit plasma. The study was approved by the local supervisory committee for studies in animal (Hannover, Germany). The y axes indicate the molar ratio of [¹⁵N]nitrate/[¹⁵N]nitrite in the rabbit plasma relative to the unlabeled nitrate (i.e., [¹⁴N]nitrate) and unlabeled nitrite ([¹⁴N]nitrite).