Objective: To explore the role of calpain in pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension and the underlying mechanisms.
Methods: Sprague-Dawley rats were randomly divided into the hypoxia group and the normoxia control group. Right ventricular systolic pressure (RVSP) and mean pulmonary artery pressure (mPAP) were monitored by a method with right external jugular vein cannula. Right ventricular hypertrophy index was presented as the ratio of right ventricular weight to left ventricular weight (left ventricle plus septum weight). Levels of calpain-1, -2 and -4 mRNA in pulmonary artery were determined by real-time PCR. Levels of calpain-1, -2 and -4 protein were determined by Western blot. Primary rat pulmonary arterial smooth muscle cells (PASMCs) were divided into 4 groups: a normoxia control group, a normoxia+MDL28170 group, a hypoxia group and a hypoxia+MDL28170 group. Cell proliferation was detected by MTS and flow cytometry. Levels of Ki-67 and proliferating cell nuclear antigen (PCNA) mRNA were determined by real-time PCR.
Results: RVSP, mPAP and right ventricular remodeling index were significantly elevated in the hypoxia group compared to those in the normoxia group. In the hypoxia group, pulmonary vascular remodeling was significantly developed, accompanied by up-regulation of calpain-1, -2 and -4. MDL28170 significantly inhibited hypoxia-induced proliferation of PASMCs concomitant with the suppression of Ki-67 and PCNA mRNA expression.
Conclusion: Calpain mediates vascular remodeling via promoting proliferation of PASMCs in hypoxia-induced pulmonary hypertension.
目的：研究钙蛋白酶(calpain)在低氧诱导肺动脉高压肺血管重构中的作用及机制。方法：SD大鼠随机分为低氧模型组和常氧对照组。插管法测定大鼠右心室收缩压及平均肺动脉压，右心室/(左心室+室间隔)比值评价右心肥厚指数，HE染色检测血管重构情况，分别采用实时荧光定量PCR和Western印迹检测肺动脉calpain-1，-2和-4 mRNA和蛋白的表达。原代培养的大鼠肺动脉平滑肌细胞分为4组：常氧对照组、常氧对照+ MDL28170(calpain抑制剂)组、低氧模型组、低氧模型+MDL28170组。MTS及流式细胞术观察细胞增殖情况，实时荧光定量PCR检测Ki-67及增殖细胞核抗原(proliferating cell nuclear antigen，PCNA) mRNA表达情况。结果：与常氧对照组大鼠比较，低氧模型组大鼠右心室收缩压、平均肺动脉压及右心肥厚指数显著增加，肺动脉血管显著重构；同时，低氧模型组大鼠肺动脉中calpain-1，-2，-4 mRNA和蛋白表达也显著上调。与常氧对照组细胞比较，低氧模型组细胞显著增殖，MDL28170可显著抑制低氧诱导的肺动脉平滑肌细胞增殖，同时逆转低氧诱导的Ki-67和PCNA mRNA表达上调。结论：calpain介导低氧诱导的肺动脉高压肺血管重构，其机制可能与介导低氧诱导的肺动脉平滑肌细胞增殖有关。.