Abstract: Abstract:Objective To explore the effect of intermittent hypoxia (IH) on RhoA/ROCK pathway in lung and on the muscularization in pulmonary vascular in rat model. Methods Wistar rats (n=40) were randomly divided into two groups: the normal oxygen control group (n=20) and the IH group ( n=20). For 4 weeks, rats in control group and IH group were ex⁃ posed to intermittent normal oxygen (21% O2) or IH (5%-21% O2) respectively. Then, mRNA transcription and protein trans⁃ lation levels of RhoA/ROCK were examined by Real-time PCR and Western blot. Expression of proliferation cell nuclear an⁃ tigen (PCNA) and α-smooth muscle actin (SM-α-actin ) of lung and pulmonary artery were detected by immunohistochemis⁃ try. Results RhoA mRNA transcription level（0.463±0.067 vs 0.182±0.040）, ROCK mRNA transcription level（0.384± 0.062 vs 0.192±0.052）, RhoA protein expression level（0.827±0.065 vs 0.424±0.075）and ROCK protein expression level （0.488±0.088 vs 0.336±0.102）were higher in IH group than those in control group（P <0.05）；Levels of PCNA in lung tissue （[ 54.67±1.80）% vs (9.14±0.91）%], PCNA in pulmonary artery （[ 49.40±1.21）% vs (8.38±1.13）%], SM-α-actin in lung tis⁃ sue [（42.66±1.63）% vs (35.44±1.41）%] and SM-α-actin in pulmonary artery [（62.62±2.53）% vs (45.54±2.58）%] were also higher in IH group than those in control group（P <0.05）. Conclusion Rho/ROCK pathway may play an important role in developing pulmonary hypertension (PH) associated with IH; and IH can promote the muscularization in pulmonary vascular to accelerate PH.

Key words: anoxia, hypertension, pulmonary, proliferating cell nuclear antigen, actins, intermittent hypoxia, pulmonary hypertension, RhoA/ROCK