Objective: Whereas it is established that endothelin-1 elicits sustained deleterious effects on the cardiovascular system during cardiopulmonary bypass (CPB), presently it remains unknown whether the inhaled administration of the dual ETA and ETB antagonist tezosentan prevents the development of pulmonary endothelial dysfunction.
Design: A prospective, randomized laboratory investigation.
Setting: University research laboratory.
Participants: Landrace swine.
Interventions: Three groups of animals underwent a 90-minute period of full bypass followed by a 60-minute period of reperfusion. Among treated groups, one received tezosentan through inhalation prior to CPB, whereas the other one received it intravenously at weaning from CPB; the third group remained untreated. Pulmonary vascular reactivity studies, realized on a total of 285 rings, were performed in all groups, including 1 sham.
Measurements and main results: The contractility of pulmonary arteries to prostaglandin F2α and to the thromboxane A2 mimetic U46619 was preserved in animals submitted to CPB. By contrast, there were significant increases both in the maximal contraction to endothelin-1 and in the plasma levels of the peptide 60 minutes after reperfusion. Tezosentan administered by inhalation or intravenously did not prevent the development of pulmonary CPB-associated endothelial dysfunction. However, while hemodynamic disturbances were improved with both routes, the inhaled administration had a beneficial effect on oxygen parameters over intravenous administration.
Conclusions: Despite the blockade of the endothelin-1 pathway with tezosentan, the development of the pulmonary endothelial dysfunction associated with CPB still occurred. However, only the inhalation route had a significant impact on gas exchange during CPB.
Keywords: CPB; endothelium; physiology/pathophysiology; pulmonary vascular resistance/hypertension; vascular tone and reactivity.
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