Related Experiment Videos
Pulmonary antioxidant enzyme activity during early development: Effect of ventilation
Raymond Foust1, Cynthia Cox, Jonathan M. Davis
1Departments of Physiology and Pediatrics (Drs. Foust, Wolfson, Miller, and Shaffer, Ms. Cox), Temple University School of Medicine, Philadelphia, Pennsylvania; and the Departments of Pediatrics (Neonatology) and the Cardiopulmonary Research Institute (Drs. Davis and Horowitz), Winthrop-University Hospital, SUNY Stony Brook School of Medicine, Mineola, New York.
Insights
Tidal liquid ventilation (TLV) and conventional gas ventilation (GV) showed minimal impact on pulmonary antioxidant enzyme (AOE) activity in preterm lambs. Developmental differences were observed, suggesting free radical mechanisms do not explain ventilation responses.
Area of Science:
- Neonatal Physiology
- Respiratory Medicine
- Biochemistry
Background:
- Premature lambs require respiratory support, with conventional gas ventilation (GV) and tidal liquid ventilation (TLV) being potential methods.
- Pulmonary antioxidant enzymes (AOE) play a crucial role in mitigating oxidative stress, particularly relevant in immature lungs.
- Understanding the impact of different ventilation strategies on AOE activity is vital for optimizing respiratory support in preterm neonates.
Purpose of the Study:
- To investigate the effects of TLV and GV on pulmonary AOE activity in preterm lambs at different gestational ages (110 and 120 days).
- To compare AOE activity between ventilated lambs and age-matched fetal controls.
- To determine if free radical-related mechanisms underlie the physiological responses to different ventilation modes.
Main Methods:
- A prospective, randomized, controlled study involving 32 preterm lambs (110 and 120 days gestation).
- Lambs were subjected to TLV, GV, or served as age-matched fetal controls.
- Arterial blood chemistries and lung histology were assessed.
- Biochemical assays measured catalase, superoxide dismutase, and glutathione peroxidase activity.
Main Results:
- Superoxide dismutase and glutathione peroxidase activity showed no significant differences based on age or ventilation method.
- Catalase activity was higher in 120-day fetal controls compared to 110-day controls.
- Catalase activity decreased in 120-day lambs (both TLV and GV) compared to controls, but not in 110-day lambs, indicating an age-specific response to ventilation.
Conclusions:
- Pulmonary AOE activity exhibits developmental differences in preterm lambs.
- The limited effect of ventilation on AOE activity suggests that free radical mechanisms are not the primary drivers of observed physiological and inflammatory outcomes.
- Further research is needed to elucidate the mechanisms underlying differential responses to TLV and GV.
Abstract:
OBJECTIVE: To examine the effect of tidal liquid ventilation (TLV) and conventional gas ventilation (GV) on the pulmonary antioxidant enzyme (AOE) activity in two groups of preterm lambs at 110 and 120 days of gestation and to compare these results to age-matched fetal controls. DESIGN: Experimental, prospective, randomized, controlled study. SETTING: School of medicine, department of physiology. SUBJECTS: Thirty-two premature lambs at 110 days (n = 16) and 120 days (n = 16) gestation. INTERVENTIONS: Six lambs at 110 and 120 days were ventilated with TLV for 4 hrs. Three lambs at 110 days were ventilated with GV for 3 hrs, and six lambs at 120 days were ventilated with GV for 4 hrs. Four lambs, each at 110 and 120 days, were used as age-matched fetal controls. Measurements: Sequential measurements of arterial blood chemistries were performed in all groups. Biochemical assays included catalase activity, superoxide dismutase activity, and glutathione peroxidase activity. Histologic examinations of lung sections from TLV and GV lungs were performed. Main Result: Despite vast differences in physiologic outcome, there were fewer differences in AOE activity as a function of ventilation (fetal control, GV, and TLV lambs) and/or gestational age. There were no significant differences in superoxide dismutase and glutathione peroxidase activity as a function of age or ventilation. Catalase activity was significantly higher (p <.05) in fetal 120-day control lambs (24.8 +/- 1.9 units/mg protein) relative to the 110-day control lambs (14.3 +/- 1.7 units/mg protein). Catalase activity significantly (p <.05) decreased in both GV and TLV 120 day lambs compared with fetal controls; yet, in the 110-day gestational lambs, there were no significant differences in enzyme level as a function of ventilation. Thus, an age-specific response to ventilation was evident for catalase activity. CONCLUSION: The present data demonstrate several developmental differences in AOE activity. The lack of ventilation effect in AOE activity, in view of the big difference in physiologic and inflammatory outcomes, suggests that mechanisms associated with free radicals do not underlie the response to different modes of ventilation.