The role of pulmonary mast cells activation and degranulation in the process of increased pulmonary artery pressure.

Hypoxia exposure often cause the increases of pulmonary arterial pressure (PAP). Studies reported that mast cells (MCs) participate in pulmonary vascular remodeling and promote the formation of chronic pulmonary hypertension. Current studies mainly focus on the change of MCs under chronic hypoxia, but few studies on the regulatory role and mechanism of MCs under acute hypoxia. Therefore, present study investigated the dynamic change of MCs in lung tissues under acute hypoxia and the role of MCs activation in the increasement of PAP. In our study, we established an experimental rat model of acute hypobaric hypoxia using a hypobaric chamber (simulated altitude of 7,000 m) and pretreated with MCs degranulation inhibitor sodium cromoglycate (SCG) to study the MCs changes under acute hypoxic exposure. We found that acute hypobaric hypoxia contributed to the increased quantity, activity, and degranulation of MCs and SCG pretreatment showed attenuated PAP elevation under acute hypoxia. Our findings implied that there is a possible mechanism of acute hypoxia cause rapid recruitment of MCs, activation, and explosive degranulation to release Tryptase, Chymase, IL-6, His, 5-HT, and Ang II, which further contributed to pulmonary microvascular contraction and increase in PAP. This work extends the knowledge about MCs, providing a potential profile of MCs as an alternative treatment for high-altitude pulmonary edema (HAPE)-related increased pulmonary artery pressure.