[Interaction between endogenous nitric oxide and hydrogen sulfide in pathogenesis of hypoxic pulmonary hypertension]

To investigate the interaction between nitric (NO) / nitric oxygenase (NOS) and hydrogen sulfide (H(2)S)/ cystathionine-gamma-lyase (CSE) system in the pathogenesis of hypoxic pulmonary hypertension.

25 rats were randomly divided into four groups: hypoxic group (n=7 ), hypoxic + L-NAME group (n=6 ), hypoxic + PPG group (n=6) and control group (n=6 ). After 21 days, pulmonary artery mean pressure (mPAP) of each rat was evaluated, and the plasma concentration of H(2)S and NO was measured. Meanwhile, the activities of CSE in pulmonary tissue in hypoxic, hypoxic + L-NAME and control groups were detected, respectively, and expressions of NOS in pulmonary arteries in hypoxic, hypoxic + PPG and control groups were also detected by immunohistochemistry technique.

mPAP was significantly increased in hypoxic rats as compared with normal controls. Meanwhile, compared with controls, the production of NO and H(2)S in plasma, the activity of CSE in pulmonary tissue and expression of NOS in pulmonary arteries were markedly decreased in hypoxic rats. However, mPAP was significantly increased in hyopxic + L-NAME group as compared with hypoxic groups, and at the same time, the plasma concentration of NO was markedly decreased. However, the plasma concentration of H(2)S and the activity of CSE in pulmonary tissue in hyopxic+L-NAME group were increased significantly as compared with those of hypoxic group. PPG also worsened pulmonary hypertension of hypoxic rats, however,it increased endogenous production of NO and the expression of NOS of pulmonary arteries obviously.

There is a negative feed back effect between NO/NOS system and H(2)S/CSE system in development of hypoxic pulmonary hypertension. They might interact with each other and therefore play an important regulating role in hypoxic pulmonary hypertension.