Prostaglandin synthesis inhibition restores hypoxic pulmonary vasoconstriction

nary vasoconstriction in blood-perfused isolated dog lungs pro-gressively diminishes with repeated hypoxic challenges. We investigated the role of prostaglandins in effecting the decay of the hypoxic response by using a double perfusion preparation that could separately perfuse the right and left lungs of a single dog. Degeneration of this response was reversed by the addition of prostaglandin (PG) synthesis inhibitors, aspirin, or indomethacin. Various PG’s known to be produced by the lung (PGE,, PGE.,, and PGF,,,), were infused, and only PGE, abol-ished hypoxic pulmonary vasoconstriction. Since other work-ers have shown that lungs can synthesize and release PG’s in response to various stimuli, we postulate that PGE, synthesis in isolated lungs may increase and thereby cause the degener-ation of the hypoxic response. The addition of aspirin or indo-methacin could inhibit the synthesis of PGE, and thereb