Effect of different amounts of arachidonic acid on vessel wall-generated PGI2 and TXA2

It has been suggested that low concentrations of AA may have vasoprotective and high concentrations vaso-damaging effects. To relate these effects to vascular generation of PGI2 and TXA2, we incubated human umbilical vein rings with AA (0, 0.01, 0.1, 1 and 2 mM) and examined the supernates for 6-keto-PGF1 alpha and TXB2. Low concentrations of AA (0.01 and 0.1 mM) caused preferential and maximal PGI2 release, whereas higher concentrations (1 and 2 mM) resulted in marked and preferential increase in TXA2 release. Disequilibrium in vascular PGI2 and TXA2 release towards the latter may relate to vaso-damaging effects of high concentrations of AA.