ABSTRACT
AIM:To observe the change of nitric oxide(NO)and hydrogen sulfide(H_2S)in blood and lung homogenate of hypoxic pulmonary hypertension(HPH)rat model,and to discuss the meaning of inhalation sodium nitrite and these factors in the treatment of HPH. METHODS:Fifty healthy male Wistar rats were assigned randomly into 5 groups(10 rats each):normoxia control group(NC),normoxia sodium nitrite group(NNI),hypoxic control group(HC),hypoxic normal saline group(HNS)and hypoxic sodium nitrite group(HNI). The mean pulmonary arterial pressure(mPAP),weight of right ventricle,weight of left ventricle plus septum,and the ratio of the weight of right ventricle to that of left ventricle plus septum(right ventricle hypertrophy index,RVHI)were also determined. The serum level of NO and plasma level of H_2S were measured,and at the same time the levels of NO in the lung homogenate were detected. The structures in pulmonary arteries were examined using optical microscope. RESULTS:After model established,compared to that in the normoxia groups,the body weight decreased significantly in hypoxia groups(P<0.05),although no difference of body weight in five groups before producing model was observed. Compared to that in normoxia groups,the levels of mPAP and RVHI increased significantly in hypoxia groups,and compared to that in hypoxia control groups and hypoxia normal saline group,mPAP and RVHI levels decreased significantly in hypoxia sodium nitrite group(P<0.05). Compared to that in normoxia groups,the serum level of NO decreased significantly in hypoxia groups(P<0.05). NO level in lung homogenate decreased significantly in hypoxia control group and hypoxia normal saline group as compared to that in normoxia groups(P<0.05),and no obvious difference between hypoxic sodium nitrite group and normoxia groups was found. The plasma level of H_2S was decreased significantly in hypoxia groups(P<0.05)as compared to that in normoxia groups. H_2S level increased significantly in hypoxia sodium nitrite group as compared to that in hypoxia control groups and hypoxia normal saline group(P<0.05). Observation under optical microscope,the lumen structure of lung in normoxia control group was normal. No significant change in normoxia sodium nitrite group was found. The proliferation of smooth muscle cells(SMCs),the collagen fiber deposition in the vessel wall and every caliber thickening was observed in hypoxic control group. The same changes were also observed in hypoxic normal saline group. The thickened caliber was relieved significantly in hypoxic nitrite group. CONCLUSION:Pulmonary hypertension and right ventricle reconstitution can be relieved by inhalation of sodium nitrite,and can be regulated by the level of NO and H_2S in rats. Above all,inhalation of sodium nitrite may degrade HPH directly or by affecting the externalization and synthesizing of gas signaling molecule indirectly.