Int J Med Sci 2019; 16(3):443-449. doi:10.7150/ijms.28353 This issue
1. Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
2. Department of Pediatrics, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
3. Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
4. Department of Otolaryngology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
5. Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
6. Department of Biomedical Science and Environmental Biology, College of Life Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
*These two authors contributed equally to this work.
Background: Hypoxia plays an important role in the vascular tone of pulmonary circulation via the vasculature and parenchymal tissue. Endothelin-1 (ET-1), a potent vasoconstrictive peptide, plays a role in inflammation in mononuclear cells. Nitric oxide synthase (NOS), which generates nitric oxide (NO)/cyclic 3', 5'-monophosphate (cGMP), is coexpressed with ET-1 in many cell types. The aim of this study was to assess whether hypoxia induces the production of ET-1 and associated expression of NOS, NO/cGMP and chemokines in rat alveolar macrophages (AMs).
Methods: NR8383 cells were cultured under hypoxic (1% oxygen) conditions for 0, 2, 4, 8 and 12 hours. Levels of ET-1, inducible NOS (iNOS), phosphorylated iNOS (p-iNOS), nitrite/nitrate (NOx), cGMP and monocyte chemoattractant protein-1 (MCP-1) were measured.
Results: ET-1, p-iNOS, NOx, and cGMP increased significantly in AMs after 4 hours of hypoxia (p < 0.05). ET-1 and MCP-1 mRNA increased after 8 hours (p < 0.05). The protein expression of ET-1, MCP-1, and p-iNOS increased in a time-dependent manner, while iNOS expression decreased with time.
Conclusions: The changes in ET-1, p-iNOS, and the NO/cGMP pathway in AMs may help elucidate the mechanisms in the hypoxic lung. Understanding changes in the endothelin axis in hypoxic AMs is a crucial first step to unravel its role in pulmonary circulation.
Keywords: hypoxia, endothelin-1, alveolar macrophage, nitric oxide synthase