Biosynthesis of prostaglandins (PGs) and effect of PGs on C-AMP content in the rabbit uterine cervical tissue at term.

The effects of prostaglandins (PGs: PGE2, PGI2 and PGF2 alpha) on contractility, PGs production by A-23187 and C-AMP production by these PGs were studied in the rabbit uterine cervical tissue at term in vitro. PGE2 or PGI2 had an inhibitory effect on the contractility; the inhibitory effect of PGE2 was more potent than that of PGI2. On the other hand, PGF2 alpha had an excitatory effect on the contractility. The mean rate of 6-keto-PGF1alpha production by A-23187 was more remarkable than those of PGE2 and PGF2 alpha. The PGE2 production was the second highest among the three PGs. The C-AMP was significantly increased by PGE2 and PGI2. The increased C-AMP level induced by PGE2 was greater than that by PGI2. On the other hand, PGF2 alpha did not increase C-AMP. From these experimental results, it seems that the production of large amounts of PGE2 and PGI2 facilitates cervical dilatation during parturition, and suggests that C-AMP participates in the cervical dilatation elicited by both PGE2 and PGI2.