Protective effect of adrenomedullin on hyperoxia-induced lung injury.

Objectives: To study the role of adrenomedullin (ADM) in hyperoxia-induced lung injury by examining the effect of ADM on the expression of calcitonin receptor-like receptor (CRLR), receptor activity-modifying protein 2 (RAMP2), extracellular signal-regulated kinase (ERK), and protein kinase B (PKB) in human pulmonary microvascular endothelial cells (HPMECs) under different experimental conditions.

Methods: HPMECs were randomly divided into an air group and a hyperoxia group (=3 each).The HPMECs in the hyperoxia group were cultured in an atmosphere of 92% O (3 L/minute) +5% CO. RT-qPCR and Western blot were used to measure the mRNA and protein expression levels of ADM, CRLR, RAMP2, ERK1/2, and PKB. Other HPMECs were divided into a non-interference group and an interference group (=3 each), and the mRNA and protein expression levels of ADM, ERK1/2, and PKB were measured after the HPMECs in the interference group were transfected with ADM siRNA.

Results: Compared with the air group, the hyperoxia group had significant increases in the mRNA and protein expression levels of ADM, CRLR, RAMP2, ERK1/2, and PKB (<0.05). Compared with the non-interference group, the interference group had significant reductions in the mRNA and protein expression levels of ADM, ERK1/2, and PKB (<0.05).

Conclusions: ERK1/2 and PKB may be the downstream targets of the ADM signaling pathway. ADM mediates the ERK/PKB signaling pathway by regulating CRLR/RAMP2 and participates in the protection of hyperoxia-induced lung injury.