The actions of histamine and prostaglandins F2α and E2 on pulmonary vascular resistance of the lung of the guinea-pig

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Abstract
In the guinea-pig isolated perfused lung, prostaglandin F2α (PGF2α) and histamine increased, and prostaglandin E2 (PGE2) decreased, resistance to fluid flow. PGF2α and histamine caused contractions of the pulmonary artery circular muscle preparation while PGE2 inhibited contractions caused by other agonists. It was concluded that the changes in resistance to fluid flow caused by the three agents was partly or wholly due to their direct action on pulmonary vascular tissue. Mepyramine abolished the pressor response to histamine but had no effect on the pressor response to PGF2α. Furthermore, there was no evidence of the involvement of adrenergic mechanisms in the action of the prostaglandins. It is suggested that PGF2α probably plays a role in the pulmonary vasoconstriction caused by anaphylaxis in guinea-pigs pretreated with mepyramine.