To investigate the effects of ginsenoside Rb1 on hypoxia/reoxygenation (H/R)-induced injury in human pulmonary endothelial cells (HPECs) and its underlying mechanism.

HPECs were randomly divided into control group(normal culture), model group(subjected to 3 h of hypoxia followed by 7 h of reoxygenation), and experimental group(pretreated with 0.1 μmol·L^-1, 1.0 μmol·L^-1, 10.0 μmol·L^-1 and 100.0 μmol·L^-1 ginsenoside Rb1 for 1 h prior to H/R). Cell viability was assessed using the CCK-8 assay. The levels of inflammatory factors including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immunosorbent assay (ELISA). The intracellular adenosine triphosphate(ATP) content and the activities of mitochondrial respiratory chain complex Ⅰ (complex Ⅰ) and ATP synthase were detected by ELISA . The protein relative expression levels of glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), zonula occludens-1 (ZO-1), vascular endothelial cadherin (VE-cadherin) and ATP synthase F1 subunit delta (ATP5D) were measured by Western blot.

The cell viability of the control group, model group and experimental group(0.1, 1.0, 10.0 and 100.0 μmol·L^-1)were 1.07±0.04, 0.61±0.06, 0.68±0.07, 0.80±0.06, 0.96±0.08 and 0.95±0.09, respectively, among which 10.0 μmol·L^-1 showed the optimal protective effect and this concentration was therefore used for subsequent experimental group. The levels of IL-1β in the control group, model group and experimental group were (136.25±3.61), (200.12±8.56) and (149.50±9.20) ng·L^-1, respectively; the levels of IL-6 were (4.95±0.26), (8.96±0.60) and (6.23±0.34)ng·L^-1, respectively; the levels of TNF-α were (328.66±19.14), (461.54±26.39) and (391.77±17.22) ng·L^-1, respectively; the relative expression levels of GRP78 were 0.84±0.15, 1.45±0.13 and 0.82±0.15, respectively; the relative expression levels of CHOP were 0.66±0.11, 1.20±0.41 and 0.76±0.14, respectively; the relative expression levels of ZO-1 were 0.81±0.11, 0.25±0.07 and 0.84±0.13, respectively; the relative expression levels of VE-cadherin were 0.75±0.12, 0.32±0.09 and 0.73±0.14, respectively; the relative expression levels of ATP5D were 0.88±0.16, 0.26±0.08 and 0.83±0.17, respectively; the activities of mitochondrial respiratory chain complex Ⅰ were 2.12±0.26, 1.40±0.17 and 1.82±0.15, respectively; the activities of ATP synthase were 2.14±0.25, 1.32±0.17 and 1.81±0.18, respectively; the contents of ATP were (86.32±8.50), (52.21±5.62) and (91.12±6.10) μmol·ug^-1 protein, respectively; there were statistically significant differences in the above indicators between the model group and the control group, between the experimental group and the model group (all P<0.05).

Ginsenoside Rb1 may alleviate H/R-induced HPECs injury, inflammatory response, and endoplasmic reticulum stress by improving mitochondrial function and increasing intracellular ATP content, thereby restoring normal cellular function.