Effect of prostaglandins E1, E2 and F2alpha and pentagrastin on the gall bladder pressure in dogs.

The effect of prostaglandins E1, E2 and F2alpha on the gall bladder pressure was studied in anesthetized dogs with and without clamping of the cystic duct. Both PGE1 and PGE2 lowered the gall bladder pressure when the initial pressure was higher than 5 mm Hg, but caused no significant change when the initial pressure was lower than 3 mm Hg. On the other hand, PGF2alpha increased the gall bladder pressure regardless of its initial pressure. When the cystic duct was clamped, PGF2alpha markedly increased the gall bladder pressure while both PGE1 and PGE2 increased it slightly. This observation suggests that the smooth muscle in the gall bladder is markedly stimulated by PGF2alpha and stimulated to a lesser degree by PGE1 or PGE2. Furthermore, PGF2alpha appears to constrict, and PGE1 or PGE2 appears to relax the sphincter of Oddi. Pretreatment with indomethacin did not affect or slightly potentiated the cholecystokinetic effect of the three prostaglandins but abolished that of pentagastrin, suggesting that prostaglandins are possible mediators for the cholecystokinetic action of the gastrointestinal hormones.