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Developmental differences in pulmonary eNOS expression in response to chronic hypoxia in the rat
Louis G Chicoine1, Jose W Avitia, Cody Deen
1Department of Pediatrics, University of New Mexico Health Sciences Center, Albuquerque 87131, New Mexico. lchicoine@salud.unm.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 19, 2002
Summary
Chronic hypoxia affects pulmonary endothelial nitric oxide synthase (eNOS) differently in adult and neonatal rats. This study reveals a developmental difference in eNOS expression and nitric oxide production in response to chronic hypoxia.
Area of Science:
- Physiology
- Pulmonary Medicine
- Developmental Biology
Background:
- Chronic hypoxia (CH) alters pulmonary endothelial nitric oxide synthase (eNOS) expression.
- Observed differences in eNOS response to CH between adult rats and neonatal pigs suggest developmental factors.
Purpose of the Study:
- To investigate if developmental differences, not species differences, explain the varied response of eNOS to CH.
- To compare the effects of CH on eNOS protein levels and nitric oxide production in adult and neonatal rats.
Main Methods:
- Adult and neonatal rats were exposed to hypobaric hypoxia or normoxia for 2 weeks.
- Measurements included body weight, hematocrit, plasma nitrite/nitrate (NOx(-)), cardiac and ventricular weights, and pulmonary arterial wall area.
- Pulmonary eNOS levels were quantified using immunoblot analysis.
Main Results:
- Both adult and neonatal hypoxic rats showed decreased body weight, elevated hematocrit, and increased right ventricular/total ventricular weight ratios.
- Hypoxic adult rats had increased pulmonary eNOS protein and plasma NOx(-) levels compared to normoxic controls.
- Hypoxic neonatal rats exhibited decreased pulmonary eNOS protein and plasma NOx(-) levels compared to normoxic neonates.
Conclusions:
- There is a significant developmental difference in pulmonary eNOS expression and nitric oxide production in response to chronic hypoxia.
- The study supports the hypothesis that developmental stage, rather than species, dictates the eNOS response to CH.