Characterization of the stimulus-response curve for hypoxic pulmonary vasoconstriction.

Lungs from seven healthy female, sea level rats were perfused and ventilated in vitro. Hypoxic pulmonary vasoconstriction was stimulated by changing the inspired gas from 21% oxygen to 6, 4, 3 or 0% oxygen (all gases contained 5% carbon dioxide and balance nitrogen). A sigmoid stimulus-response curve was derived by probit analysis with a 50% of maximum response (ED50) at an oxygen tension of 3.49 +/- 0.17 kPa. It is suggested that such characterizations of the response to hypoxia may allow a more precise comparison of the effects of species, age, sex and drugs on hypoxic pulmonary vasoconstriction.