Altered prostanoid formation in human umbilical vasculature in response to variations in oxygen tension

Prostanoid formation in human umbilical vessels perfused was assessed at different oxygen tensions. At an atmosphere of 5% oxygen the production rate of prostacyclin (measured as 6-keto-PGF_1α) was higher, while those of thromboxane A₂ (measured as TXB₂), PGE₂ and PGF_2α were lower than with 20%, 50% and 95% oxygen. The stimulatory effect of angiotensin II on prostanoid production was found to be independent on the prevailing oxygen tension. Vascular formation of prostanoids thus seems to be at least partially affected by the ambient oxygen tension. Though altered oxygen tension does not seen to affect angiotensin induced prostanoid formation, the action of other vasoactive agents influencing vascular formation of prostanoids may respond differently to hypoxia or hyperoxia.