Isolation of pulmonary pressor substances from bovine amniotic fluid

The pulmonary pressor activity of bovine amniotic fluid resides in substances that appear to be non-polar lipids as suggested by the various chemical and chromatographic procedures. In preliminary experiments, it was found that the pressor activities of the hexane extracts were blocked by prior administration of aspirin to the calf (1 mg/kg), suggesting that pressor effect was mediated via the prostaglandin system. The amniotic fluid lipids, however, differed from the known prostaglandins in being less polar as indicated by thin layer chromatography and in possessing greater pressor activity. It is possible, of course, that the lipids with pulmonary pressor activity participate in the metabolism of the prostaglandins.