期刊
AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY
卷 284, 期 6, 页码 L964-L971出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajplung.00421.2002
关键词
pulmonary hypertension; persistent pulmonary hypertension of the newborn; lung hypoplasia; congenital diaphragmatic hernia; angiogenesis
资金
- NHLBI NIH HHS [K08 HL073893] Funding Source: Medline
In addition to its vasodilator properties, nitric oxide ( NO) promotes angiogenesis in the systemic circulation and tumors. However, the role of NO in promoting normal lung vascular growth and its impact on alveolarization during development or in response to perinatal stress is unknown. We hypothesized that NO modulates lung vascular and alveolar growth and that decreased NO production impairs distal lung growth in response to mild hypoxia. Litters of 1-day-old mouse pups from parents that were heterozygous for endothelial nitric oxide synthase ( eNOS) deficiency were placed in a hypobaric chamber at a simulated altitude of 12,300 ft (FIO2 = 0.16). After 10 days, the mice were killed, and lungs were fixed for morphometric and molecular analysis. Compared with wild-type controls, mean linear intercept (MLI), which is inversely proportional to alveolar surface area, was increased in the eNOS-deficient (eNOS -/-) mice [51 +/- 2 mum (eNOS -/-) vs. 41 +/- 1 mum (wild type); P < 0.01]. MLI was also increased in the eNOS heterozygote (+/-) mice (44 +/- 1 mu m; P < 0.03 vs. wild type). Vascular volume density was decreased in the eNOS -/- mice compared with wild-type controls ( P < 0.03). Lung vascular endothelial growth factor ( VEGF) protein and VEGF receptor-1 (VEGFR-1) protein content were not different between the study groups. In contrast, lung VEGFR-2 protein content was decreased from control values by 63 and 34% in the eNOS -/- and eNOS +/- mice, respectively ( P < 0.03). We conclude that exposure to mild hypoxia during a critical period of lung development impairs alveolarization and reduces vessel density in the eNOS-deficient mouse. We speculate that NO preserves normal distal lung growth during hypoxic stress, perhaps through preservation of VEGFR-2 signaling.
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