2.2. Protocols for animal experiments
Upon arrival, SD rats were adapted to the environment for 1 week, and were subsequently assigned in a random manner into experimental groups: the normoxia group exposed to normobaric normoxia (21% O2) for 3 weeks versus the hypoxia group placed in a hypoxic chamber (10% O2) for 3 weeks. After 3 weeks, rats were anesthetized with 3% isoflurane. Right ventricular systolic pressure (RVSP) and rat body weight were measured to evaluate the PH model. The right, left ventricle (RV, LV), the interventricular septum (IS) and tibia were dissected and measured for weight or length in order to calculate the ratio of RV to (LV+IS) & RV to tibial length, a key index for RV hypertrophy. After thoracotomy, blood was rapidly collected into EDTA-anticoagulant tube and mixed immediately to avoid clotting. The freshly isolated pulmonary arterial samples were used to assay protein expression. The right lower lobe of the lung was fixed in 4% paraformaldehyde (PFA) for hematoxylin-eosin (HE), immunofluorescence (IF) and immunohistochemistry staining.
The WT and Olr1-/- rats, 6-7-week-old, were also assigned randomly into 4 groups as follows: WT rats exposed to normobaric normoxia (21% O2) for 3 weeks (WT-Normoxia),Olr1-/- rats exposed to normobaric normoxia (21% O2) for 3 weeks (Olr1-/- -Normoxia), WT rats exposed to hypoxia (10% O2) for 3 weeks (WT-Hypoxia), andOlr1-/- rats exposed to hypoxic condition (10% O2) for 3 weeks (Olr1-/- -Hypoxia). Detection of various indicators and harvest of tissue were identical to the SD rats.