Objective: The aim of this study is to investigate the effects of L-arginine, the substrate of nitric oxide (NO) on the duration of nitric oxide selective decrease of pulmonary hypertension. To assess whether combined use of inhaled nitric oxide and venous administered L-arginine can improve the efficacy of inhaled NO on the inhibition of hypoxia induced pulmonary hypertension.
Method: Eight pigs with hypoxic pulmonary hypertension received either inhaled NO(12-15 ppm) for 10 minutes or inhaled NO plus venous administrered L-arginine(10 g), then hemodynamic parameters were recorded.
Result: NO inhalation significantly inhibited hypoxic induced pulmonary hypertension with pulmonary arterial pressure decreasing from 4.2 +/- 0.4 kPa to 2.5 +/- 0.5 kPa(P < 0.01) and pulmonary vascular resistance from 56 +/- 25 kPa.s.L-1 to 31 +/- 13 kPa.s.L-1(P < 0.01), but this just lasted for 3-5 minutes after stopping inhalation; combined use of L-arginine infusion did not further decrease pulmonary arterial pressure, but significantly prolonged the inhibitory effect of inhaled NO on pulmonary hypertension (20 times) as compared with inhaled NO only.
Conclusion: With the existence of exogenous NO, supplement of NO substrate L-arginine produced a synesgetic inhibition effect on hypoxic induced pulmonary hypertension.