Abstract 12435: The Hypoxic Influence on Right Ventricular Systolic Pressure (RVSP) in the SuHx-model
Rationale: The SuHx model is based on the combined exposure of rats to the Vascular Endothelial Growth Factor receptor inhibitor SU5416 and hypoxia and has histological features resembling plexogenic pulmonary vascular remodeling in human pulmonary arterial hypertension (PAH). This study aimed to assess vascular reactivity to oxygen exposure in the SuHx model. RVSP was measured continuously by telemetry and the effects were determined of acute exposure to hyperoxic air of previously hypoxic animals.
Methods: A telemetry device was inserted using a transdiaphragmatic approach and the tip of the catheter was placed in the right ventricle. To respect the circadian rhythm, data collected between 10 and 11 PM each day was used for analysis. SuHx animals received SU5416 one week after surgery and both SuHx and Hx-only animals were husbanded at 10% inspired oxygen for 4 weeks. Animals underwent echocardiography weekly in an enriched oxygen condition (60%). During the enriched oxygen condition, telemetric RVSP was measured in bins of 1 minute.
Results: After two weeks of hypoxic exposure, SuHx and Hx-only animals had responded with a similar increase in RVSP. From week 3 onwards, SuHx maintained an increased RVSP compared to Hx-only animals. Direct upon re-exposure to normoxic air, RVSP decreased in both groups but remained higher in SuHx animals. Acute reversibility was present during the hypoxic phase in both groups, however, SuHx animals showed a larger decrease of vascular reactivity during the entire experiment.
Conclusion: Pulmonary hypertension in the SuHx model is partially reversible upon reexposure to normoxic air. Vascular reactivity plays a major role in the model, both during hypoxic exposure and after re-exposure to normoxic air.
- © 2012 by American Heart Association, Inc.