ABSTRACT
<p><b>AIM</b>Pulmonary hypertension is a common complication of congenital heart disease with a left-to right shunt. The mechanism of pulmonary hypertension induced by high pulmonary blood flow is still not fully understood. Recent studies showed that hydrogen sulfide (H2S) could relax vascular smooth muscle cells. But the change of the system of H2S in pulmonary hypertension induced by high pulmonary blood flow was not reported. We studied the influence on expression of CSE mRNA and production of hydrogen sulfide in rat lung tissues by L-Arginine, in order to demonstrate a regulating role of nitric oxide (NO) in the regulation of cystathionine-gamma-lyase/hydrogen sulfide system (CSE/H2S).</p><p><b>METHODS</b>Thirty male SD rats were randomly divided into shunting group, shunting with L-Arginine group, and control group. Abdominal aorta and inferior vena cava shunting was produced in rats of the later group. Pulmonary artery mean pressure (mPAP) and the hypertrophy of right ventricle of each rat were analyzed. The expression of lung tissue CSE mRNA was measured using quantitative reverse transcription-polymerase chain reaction and in situ hybridization. The activity of CSE in lung tissue was measured according to chemical analysis.</p><p><b>RESULTS</b>mPAP was significantly increased in shunted rats compared with normal control (P < 0.01), the expression of lung tissue CSE mRNA and the activity of CSE in lung tissue were decreased in shunt group (P < 0.01). However, L-arginine significantly attenuated pulmonary artery pressure, but augmented the expression of lung tissue CSE mRNA as well as the activity of CSE in lung tissue.</p><p><b>CONCLUSION</b>L-Arginine reverses the down-regulation of CSE/H2S system in high pulmonary blood flow-induced pulmonary hypertension.</p>