[Changes in the vascular endothelium in fetal rabbits during perfusion in vitro]

Under perfusion conditions in vitro the morphologic state of preparations of fetal vessels of the ductus arteriosus and the pulmonary artery was studied by light and electron microscopy. At maintaining standard conditions of perfusion experiments, manipulation of vessels did not result in substantial changes of the endothelium. Storage of the vessel preparations at 4 degrees C for 24 hours did not induce marked morphologic changes, yet the vessels exhibited increased constriction reactivity to noradrenaline which resulted in severe damage of the endothelial lining. Perfusion of the ductus arteriosus by oxygen saturated solution led to vessel constriction and severe endothelial damage. The observed changes should be taken into account on evaluating responses of vascular segments to vasoactive substances.