PGI2 enhanced cAMP content in bovine coronary arteries in the presence of isobutylmethylxanthine.

Incubation of bovine coronary artery (BCA) rings with isobutylmethylxanthine (IBMX) resulted in a time-dependent increase of cAMP content. This effect was blocked, when the rings were preincubated with indomethacine or 15-hydroperoxy-arachidonic acid for 5 min, indicating that the IBMX-induced increase in cAMP content may depend on endogenous PGI2 formation. PGE2 did not increase the cAMP content in BCA rings. Dipyridamole did not effect cAMP content, when used as a substitute for IBMX. It is suggested that PGI2 stimulates cAMP formation in arterial walls, but that this effect only becomes visible in the presence of a phosphodiesterase inhibitor.