ABSTRACT
Prostacyclin (PGI2) is a term coined by Moncada et al. 1 for a biologically active product generated from arachidonic acid (AA) and the prostaglandin endoperoxides by bovine aorta. The pathway for the formation of this product had earlier been shown to exist in the rat stomach by Pace-Asciak and Wolfe, 2 who also isolated and identified the stable end product of this pathway, 6-keto PGFlα, during incubations of AA or prostaglandin endoperoxides with homogenates of the rat stomach. 3,4 Under acidic conditions, PGI2 is converted into 6-keto PGFlα, although it is quite stable to alkaline conditions. 5 The PGI2 skeleton consists of a derivative of prostanoic acid containing an ether linkage between carbon atoms 6 and 9 (see Figure 1). As with other prostaglandins, the PGI2 family is derived from certain methylene interrupted cis polyunsaturated fatty acids; the structural requirements are more restricted for PGI2 synthesis in that a Δ5 double bond is an essential requirement for 6(9) oxy ring formation (see Figure 2).
