Investigations into the mechanism by which sodium fluoride stimulates prostaglandin production in guinea-pig uterus

Sodium fluoride (10 mM) caused a slow increase in the outputs of PGF-2 alpha, 6-keto-PGF-1 alpha and, to a lesser extent, PGE-2 from the Day-7 and Day-15 guinea-pig uterus superfused in vitro. This stimulatory action of sodium fluoride was not prevented by using calcium-free Krebs' solution. There was also a faster stimulation of 6-keto-PGF-1 alpha output from the Day-7 guinea-pig uterus produced by sodium fluoride, and this quicker response was abolished by using calcium-free Krebs' solution. TMB-8 (an intracellular calcium antagonist) inhibited the stimulatory action of sodium fluoride on the outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 guinea-pig uterus. W-7 and trifluoperazine (calmodulin antagonists) and neomycin (an inhibitor of phospholipase C) had no inhibitory effect on the increases in outputs of PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from the Day-7 guinea-pig uterus produced by sodium fluoride. These results indicate that sodium fluoride slowly stimulates uterine PGF-2 alpha, PGE-2 and 6-keto-PGF-1 alpha synthesis in the guinea-pig uterus by mobilizing intracellular calcium by a mechanism which apparently does not involve the activation of phospholipase C or the participation of calmodulin (or a related compound). The initial, faster stimulation of 6-keto-PGF-1 alpha synthesis in the Day-7 guinea-pig uterus by sodium fluoride is dependent upon extracellular calcium.