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Oxygen toxicity in the infant rhesus monkey: effects on regulatory peptides in lung and blood
I M Keith1, R Ekman, P M Farrell
1Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706.
Insights
High oxygen ventilation in infant monkeys altered lung regulatory peptides, with some levels decreasing less in oxygen-exposed groups. No blood marker for oxygen toxicity was identified.
Area of Science:
- Neonatal physiology
- Pulmonary medicine
- Biochemistry
Background:
- Mechanical ventilation is critical in neonatal intensive care.
- High oxygen concentrations can cause lung injury.
- Regulatory peptides in the lung may play a role in oxygen toxicity.
Purpose of the Study:
- To investigate the impact of high oxygen ventilation on pulmonary regulatory peptides in infant rhesus monkeys.
- To identify potential blood-borne peptide markers for early detection of oxygen toxicity.
Main Methods:
- Ten infant rhesus monkeys were ventilated with >95% oxygen or room air.
- Lung tissue and blood samples were collected at 6, 12, and 24 hours.
- Radioimmunoassay was used to quantify gastrin-releasing peptide (GRP), CGRP, PYY, VIP, and somatostatin (SOM).
Main Results:
- Tissue levels of GRP, CGRP, and PYY decreased over time, potentially due to ventilation.
- GRP and CGRP levels were higher in oxygen-ventilated infants at 24 hours compared to controls.
- VIP levels were lower in oxygen-ventilated infants at 24 hours.
- No significant changes in blood peptide levels were observed with oxygen treatment.
Conclusions:
- Ventilation with >95% oxygen alters tissue concentrations of pulmonary regulatory peptides in infant monkeys.
- Specific peptide changes may indicate altered responses to oxygen exposure.
- A reliable blood-borne peptide marker for oxygen toxicity was not identified in this study.
Abstract:
A total of ten 6-month-old male rhesus monkey (Macaca mulatta) infants, born full-term, were positive-pressure ventilated with greater than 95% oxygen or room air (controls). A protocol was used which closely simulated pediatric intensive care. To test if regulatory peptides were affected by the oxygen treatment, and to search for an early marker of oxygen toxicity, lung tissue samples and systemic mixed venous blood were collected at 6, 12 and 24 hours after onset of treatment. The peptides, gastrin releasing peptide (GRP), calcitonin gene-related peptide (CGRP), peptide YY (PYY), vasoactive intestinal peptide (VIP) and somatostatin (SOM), were quantitated in lung tissue extracts and plasma using radioimmunoassay. Lung tissue GRP, CGRP, and PYY levels appeared to decrease gradually with time, perhaps as a result of the positive pressure ventilation procedure. GRP and CGRP levels decreased less among monkey infants ventilated with oxygen, thus they were significantly higher at 24 hours than in air ventilated controls. VIP levels were significantly lower among tests compared to controls at that time. Blood peptide levels did not change with oxygen treatment. These results suggest that tissue concentrations of certain pulmonary regulatory peptides can become altered by ventilation with greater than 95% oxygen. A blood borne peptide marker was not identified.