Effects of indomethacin on prostaglandin synthesis and on contractile response of the guinea pig gallbladder.

In studies on prostaglandin (PG) synthetase activity in the guinea pig gallbladder, prostaglandin E2 and F2 alpha (PGE2 and PGF2 alpha) were enzymatically formed from arachidonic acid using the 105,000-g precipitate fraction. The amount of PGE2 synthesized was about four times larger than PGF2 alpha. Indomethacin (1-3 microM) inhibited both the PG synthesis and the contractile response to transmural stimulation in the gallbladder. These findings suggest that the inhibitory effect of indomethacin on the contractility of the gallbladder is related to the inhibition of PG synthesis, and that endogenous PGE2 is involved in the contractility of this tissue.