洛沙坦对蛋白激酶C在慢性缺氧大鼠模型肺动脉胶原表达作用的影响

目的　观察洛沙坦对蛋白激酶C(PKC)在慢性缺氧大鼠模型肺动脉胶原表达作用的影响。方法　将二级SD大鼠分为 3组 :A组 (正常对照组 )大鼠室内常规饲养。B组 (单纯缺氧 4周组 )大鼠置于常压低氧舱中 ,舱内充入氮气 ,使氧浓度维持在 (1 0 0± 0 5) % ,每天 8h ,每周 6d ,连续 4周 ;大鼠每天缺氧前用 2ml蒸馏水灌胃。C组 (洛沙坦干预组 )缺氧条件同B组 ,大鼠每天缺氧前用洛沙坦 (洛沙坦 50mg/kg溶于 2ml蒸馏水 )灌胃。采用透射电镜、放射活性测定法、免疫组化、原位杂交等方法观察 3组大鼠肺细小动脉超微结构、肺组织PKC活性、肺动脉管壁PKC免疫组化及Ⅰ、Ⅲ型胶原和Ⅰ、Ⅲ型前胶原基因表达的变化。结果　 (1 )B组大鼠平均肺动脉压、右心室重量比显著高于A组(P <0 0 1 ) ,C组显著低于B组 (P <0 0 1 )。 (2 )光镜下可见B组大鼠肺血管管壁厚度占血管外经的百分比、管壁面积占管总面积的百分比显著高于A组 (P <0 0 1 ) ,C组显著低于B组 (P <0 0 1 )。电镜下可见B组大鼠肺动脉胶原纤维较A组明显为多 ,C组较B组明显为少。 (3)B组大鼠肺组织细胞PKC总活性、胞膜PKC活性、胞质PKC活性及胞膜PKC活性占PKC总活性的百分比显著高于A组(P <0 0 1 ) ,C组上述指标均显著低于B组 (P <0 0 1 )。 (4)免疫组化显示 ,B

The effect of losartan intervention on the regulation of pulmonary arterial collagen expression by protein kinase C in chronic hypoxic rat models

OBJECTIVE: To investigate the regulating role of protein kinase C(PKC) and the effects of losartan intervention on the expression of pulmonary arterial collagen in chronic hypoxic rat models. METHODS: Thirty six rats were randomly divided into three groups: healthy control group(A), hypoxic model group(B),and hypoxic + losartan intervention group (C). MT% (vessel medial thichness/ total thichness) and WA% (vessel wall area/total area) of pulmonary arterioles were measured with light microscopy,the ultrastructures of pulmonary arterioles were observed by electronic microscope, the PKC activities of lung tissues were detected with radioactive method,the protein and(or) mRNA expression of PKC and collagen I, III in arterioles were observed using immunohistochemistry and in situ hybridization. The relative contents integral light density(LD)] of PKC, collagen I, III and procollagen I, III mRNA in pulmonary arterioles were calculated with image analysor. RESULTS: (1) The mean pulmonary arterial pressure and weight ratio of right ventricle (RV) to left ventricle(LV)+septum( S)(RV/LV+S) in group B were significantly higher than those in group A(P < 0.01), but in group C they were significantly lower than those in group B (P < 0.01). (2) MT% and WA% of pulmonary arterioles in group B were significantly increased than those in group A (P < 0.01) while in group C both the parameters were significantly decreased than those in group B (P < 0.01). Collagen fiber deposition in pulmonary arteriolar walls were inhibited in group C by electronic microscopy.(3) The total,cytoplasmic and cytomembrane PKC activities, as well as the ratio of cytomembrane PKC activity to total one in group B were significantly increased than those in group A(P < 0.01),while all these parameters in group C were significantly decreased than those of group B (P < 0.01). (4)LD of PKC,collagen I and procollagen I m RNA expressions in pulmonary arterioles were significantly increased in group B than those in group A(P < 0.01), but in group C they were significantly decreased than those in group B(P < 0.01). There were no significant differences in collagen III and procollagen IIImRNA expressions among the three groups(P > 0.05).(5)Significant positive correlations were found between the PKC activities and collagen I expressions(P < 0.05) and between the expressions of PKC and collagen I in pulmonary arterioles(P < 0.01). CONCLUSIONS: The PKC signal pathway participated the regulation of pulmonary arterial collagen expression in chronic hypoxic rat models and may play an important role in the pathogenesis of pulmonary hypertension and structural remodeling of pulmonary arterials. Losartan could reduce the hypoxic pulmonary hypertension by interference the role of PKC on pulmonary arterial collagen expression.