Iloprost (ZK 36374) prevents angiotensin I conversion in the isolated perfused rat lung against anoxia.

The tissue protective effect of iloprost against anoxia was studied in the isolated perfused rat lung. The change in angiotensin converting enzyme activity was taken as a sign of the biochemical activity of pulmonary vascular endothelium and was measured by bioassay of the vasoconstrictor effects of angiotensin I and angiotensin II. A significant decrease in angiotensin converting enzyme activity was observed in the lungs incubated with Krebs alone and exposed to anoxia for 2 h. The decrease in angiotensin converting enzyme activity following anoxia for 2 and 24 h was prevented by prior pretreatment with iloprost. The pulmonary vasoconstrictor effect of angiotensin II was significantly enhanced following anoxia and iloprost prevented this potentiation. The prevention by iloprost of the decrease in angiotensin converting enzyme activity and increase in the pressor response to angiotensin II was attributed to damage of pulmonary vascular endothelium during anoxia. Possible underlying mechanisms are discussed.