Acute hypobaric hypoxia augments ROCK2 protein level and activity

Aim: Rho kinase activation plays an important role in hypoxic pulmonary vasoconstriction and increased vascular resistance. The present study investigated changes in the level and activity of rho kinase isoform 2 (ROCK2) under acute hypobaric hypoxia exposure. For this, Wistar rats were taken as the model organism. Materials and Methods: Fifteen male Wistar rats (4-6 week old, 250 grams) were normalized with the surrounding environment by providing a 12/12 hour day and night acclimatization cycle. The rats were divided into 3 groups: (a) control group (no exposure, n = 5), (b) Group 1 (12 hour hypobaric-hypoxia exposure, n = 5) and (c) Group 2 (12 hour hypobaric hypoxia and 12 hour normobaric normoxia exposure, n = 5). A change in behavior of the animals was noted before sacrifice. Blood was collected from the beating heart of the anesthetized animal. Lungs were dissected out and used to estimate the levels and activity of ROCK2 in different groups using commercially available kits. Lung histology was evaluated by immunohistochemistry. ROCK2 gene expression was studied in the blood and lungs using quantitative PCR. Results and Conclusions: Control and Group 2 animals had an active movement while the Group 1 animals were sluggish before the sacrifice. Formation of a large perivascular edema cuff and collagen deposition in lungs of Group 1 and a reduction in Group 2 was observed. The protein levels and activities of ROCK2 were increased in Group 1 (p < 0.05) and became normal in Group 2 which was akin to control group animals. ROCK2 expression in PBMCs was increased in Group 1 (10.7 fold, p = 0.005) and was decreased in Group 2 (5.5 fold, p = 0.02). The outcomes establish that acute hypobaric hypoxia augments ROCK2 protein level and activity.