Gestational resistance to the pulmonary vasoconstrictor effect of the TxA2 mimetic U-46619: possible mechanism

The effects of rabbit gestation on the pulmonary vascular pressor effects of U-46619 and downregulation of the thromboxane A2 receptors were analyzed in mechanically ventilated non-pregnant rabbits. Administration of U-46619 in mechanically ventilated non-pregnant rabbits stimulated vascular tone which were blunted late in pregnancy. Furthermore, the attenuation of pulmonary vascular response to the thromboxane analog protected the rabbits from the CO- and mean systemic arterial pressure-reducing effects of the compound.