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Platelet-activating factor induces selective pulmonary arterial hyperreactivity in isolated perfused rabbit lungs
J A Ohar1, K S Waller, T E Dahms
1Department of Internal Medicine, St. Louis University Medical Center, Missouri 63110-0250.
The American Review of Respiratory Disease
|July 1, 1993
Summary
Chronic platelet-activating factor (PAF) treatment in rabbits enhances pulmonary arterial reactivity to specific vasoconstrictors, contributing to pulmonary hypertension (PHT). This study highlights altered vasoreactivity in PAF-induced PHT.
Area of Science:
- Cardiovascular Physiology
- Pulmonary Hypertension Research
- Pharmacology
Background:
- Pulmonary hypertension (PHT) is a complex condition with various underlying mechanisms.
- Platelet-activating factor (PAF) is implicated in inflammatory and cardiovascular processes.
- Understanding the role of vasoreactivity in PAF-induced PHT is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the role of altered pulmonary vasoreactivity in the development of PAF-induced pulmonary hypertension.
- To assess the steady-state pulmonary vascular response to selected vasoconstrictors in a rabbit model of chronic PAF administration.
Main Methods:
- Isolated, perfused rabbit lungs were used to evaluate pulmonary vascular responses.
- Rabbits were treated with PAF for 28 days to establish a model of chronic PHT.
- Pulmonary arterial pressure and resistance were measured following administration of vasoconstrictors: PGF2 alpha, norepinephrine, angiotensin II, PAF, and KCl.
- Vascular resistance partitioning was performed using the vascular occlusion method.
Main Results:
- Chronic PAF treatment significantly increased pulmonary arterial pressure and pulmonary vascular resistance (PVR) compared to controls.
- PAF-treated lungs exhibited enhanced reactivity to PGF2 alpha and norepinephrine.
- Arterial resistance constituted a larger proportion of PVR during norepinephrine and PGF2 alpha challenges in PAF-treated lungs.
- Responses to angiotensin II, acute PAF, and KCl were not significantly different, with a blunted response to acute PAF in treated lungs.
Conclusions:
- Chronic PAF administration leads to enhanced pulmonary arterial reactivity to specific vasoconstrictors, contributing to the pathogenesis of pulmonary hypertension.
- The study demonstrates a shift in vascular resistance towards the arterial segments in response to certain vasoconstrictors in PAF-induced PHT.
- These findings underscore the importance of vasoreactivity in the sustained elevation of pulmonary vascular resistance in this model.