The effects of PGF2 alpha on respiratory and cardiovascular variables in pig.

PGF2 alpha was injected into different parts of the circulatory system (intravenously by femoral and jugular veins, into the pulmonary artery, into the ascending or descending aorta and into the internal carotid artery at a level above the sinus and carotid body) of anaesthetized spontaneously breathing pigs. It caused changes in respiratory and cardiovascular variables. In vagosympathectomized animals the changes in pattern of breathing produced by PGF2 alpha were greatly reduced and total lung resistance was increased. This may indicates more than one site of action of PGF2 alpha, lung resistance being influenced by a direct action of PGF2 alpha and by an immediate reflex while the pattern of breathing being modulated by vagal efferents from the lungs.