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Circulating immunoreactive endothelin-1 in children with pulmonary hypertension. Association with acute hypoxic
S W Allen1, B A Chatfield, S A Koppenhafer
1Department of Pediatrics, University of Colorado School of Medicine, Denver.
Insights
Circulating endothelin-1 (ET-1) levels are elevated in children with pulmonary hypertension (PH). These elevated ET-1 levels correlate with pulmonary vasoreactivity during acute hypoxia, suggesting a role in PH.
Area of Science:
- Pediatric Cardiology
- Pulmonary Hypertension Research
- Vascular Biology
Background:
- Pulmonary hypertension (PH) in children is a serious condition.
- Endothelin-1 (ET-1) is a potent vasoconstrictor peptide.
- The role of ET-1 in pediatric PH and its relation to hypoxic pulmonary vasoconstriction is not fully understood.
Purpose of the Study:
- To investigate circulating endothelin-1 (ET-1) levels in children with PH.
- To determine if ET-1 levels correlate with the degree of hypoxic pulmonary vasoconstriction.
Main Methods:
- Measured arterial and mixed venous plasma concentrations of immunoreactive ET-1 (irET-1) in 13 children during cardiac catheterization.
- Included children with various diagnoses of PH and healthy controls.
- Assessed changes in pulmonary artery pressure (Ppa) during acute hypoxia.
Main Results:
- Plasma irET-1 levels were significantly elevated in children with PH compared to non-PH controls (12.3 +/- 3.4 vs. 3.6 +/- 0.7 pg/ml).
- Basal irET-1 levels showed a strong correlation with the increase in mean Ppa during acute hypoxia (r = 0.69).
- No significant difference in arterial/venous irET-1 ratios was observed between groups.
Conclusions:
- Circulating irET-1 levels are frequently elevated in children with pulmonary hypertension.
- Elevated irET-1 levels are strongly associated with pulmonary vasoreactivity during acute hypoxia in children.
- The direct contribution or marker status of elevated irET-1 in pediatric PH requires further investigation.
Abstract:
To determine whether circulating levels of endothelin-1 (ET-1), a potent vasoconstrictor peptide, are elevated in children with pulmonary hypertension and related to the degree of hypoxic pulmonary vasoconstriction, we measured arterial and mixed venous plasma concentrations of immunoreactive ET-1 (irET-1) in 13 children during cardiac catheterization. Clinical diagnoses in seven children with pulmonary hypertension (PH) included chronic lung disease (four children), congenital heart disease after surgical repair (two children), and primary ("reactive") pulmonary hypertension (one child). Blood samples were simultaneously obtained from pulmonary artery (venous) and systemic arterial sites during baseline conditions. Plasma irET-1 was elevated in children with PH (12.3 +/- 3.4 versus 3.6 +/- 0.7 pg/ml, PH versus non-PH; p < 0.01). Arterial/venous irET-1 ratios in the PH group (1.1 +/- 0.2) were not different from those in the non-PH group. During acute hypoxia, mean Ppa increased from 27 +/- 3 to 40 +/- 5 mm Hg. Basal irET-1 correlated strongly with the degree of elevation of mean Ppa during acute hypoxia (r = 0.69; p < 0.02). We conclude that irET-1 levels are often elevated in children with PH, and they are strongly correlated with pulmonary vasoreactivity during acute hypoxia. Whether elevated irET-1 levels contribute directly to or are markers of altered pulmonary vascular tone and reactivity in children with PH remains speculative.